于非闇从46岁才开始研究工笔花鸟画，起步虽晚，但大器晚成，成就极大。这与他曾学过园艺学、鸟类学,为后来画工笔花鸟画打下基础。到了40年代其名声与张大千不相上下。他研究工笔花鸟画，从学清代陈洪绶入手，后学宋、元花鸟画，并着意研究赵佶手法。在古物陈列所工作期间，接触到不少古画，开扩了眼界，提高了画艺。作画主张师古而不泥古，更重师法造化。能再现一草一叶瞬间动态特点，而不似静物之拘板。除学习卷轴画外，又学宋纯丝古朴的装饰手法。在勾线用笔上吸收了书法的方法，填色上主张柔婉鲜华，表现出形象的气骨。反对过于工巧细密而失掉笔墨高韵和整体精神。作画不墨守成规，敢于创新。白描兰竹水仙，生动传神，秀雅清逸，所画牡丹能将春之花、夏之叶、秋之干萃于一枝。源于现实而高于现实，尽与自然相吻合。书法为瘦金体，兼善治印。
于非闇的艺术特色可以从其师承关系上得知。陈洪绶对于非闇的影响巨大。陈洪绶，字章侯，号老莲。诸暨(今浙江诸暨)人。性情孤傲倔强，崇祯时为监生，召为内廷供奉，不就；明亡后，清兵入浙东，出家为僧，号悔迟、老迟。善诗，工书法，长于绘画。擅人物、山水、花鸟、竹石等，以工笔人物著称。所画人物躯干伟岸，衣纹线条细劲清圆，晚年则形象夸张，或变态怪异，性格突出。花鸟等描绘精细，设色清丽，富有装饰味。亦能画水墨写意花卉，酣畅淋漓。还长于为文学作品创作插图，能表现出原作人物的精神气质。其画手法简练，色彩沉着含蓄，格调高古，享誉明末画坛，与北方的崔子忠并称“南陈北崔”。而陈洪绶又师法武林派蓝瑛和宋代李公麟。蓝瑛擅画山水，落笔纵横奇古，风格秀润。集取晋、唐、两宋，遍摹元代诸家笔法之优长。其画风是从多方面变代出来的。晚年作品渐趋苍劲疏宕。画风又有多种面貌，有些作品笔墨含蓄隽雅，有些作品青绿重设色，画法工细，色调浓丽，愈老而愈工。晚年他的笔法益苍劲，颇类沈周。他兼工人物、花鸟、兰竹、俱得古人三昧。李公麟，字伯时，安徽桐城人，博学多能，绘画题材多样，技术全面，不仅精于人物鞍马、神仙佛道，也能做一些山水、花鸟。确立了“白描”画法的创作形式。

于非闇46岁左右开始画工笔花鸟画，从学清代陈洪绶入手，后学宋、元花鸟画，并着意研究赵佶手法。重古意是于非案的一大特点，他在生命的最后一年，于病中作了一幅《喜鹊柳树》，在题跋中写道：“从五代两宋到陈老莲是我学习传统第一阶段，专学赵佶是第二阶段，自后就我栽花养鸟一些知识从事写生，兼汲取民间画法，但文人画之经营位置亦未尝忽视。如此用功直到今天，深深体会到生活是创作的泉源，浓妆艳抹、淡妆素服以及一切表现技巧均以此出也。”这是他对一生艺术里程的重要总结。但师古而不泥古，创两宋双勾技法之新，自成画派。构图打破陈规，用笔刚柔相济，着色求艳丽而不俗。如画牡丹，取春之花、夏之叶、秋之干而成，既能远观，又可近赏。且善于在画上题诗跋文，配以自刻印章，使画面饶有意趣。他艺风严谨，订有日课，未曾稍懈。在古物陈列所工作期间，接触到不少古画，并且经常出没于古董店，借古画临摹，汲取许多技法。还到北京故宫研究名作，开扩了眼界，提高了画艺。到沈阳故宫临摹黄筌《写生珍禽图)及赵佶《瑞鹤图》，继承现实主义传统。除学习卷轴画外，又学宋纯丝古朴的装饰手法。
于非闇的工笔花鸟不仅得李公麟之笔法，蓝瑛之多变的风格，还体现着陈洪绶的高古之风趣。《仿宣和御笔花鸟》于疏廓里见真意。尤其画中羽毛鲜艳的小鸟，微微仰头的一瞬，极显天真古趣，最能传达画外之意。在此基础上，于非闇的绘画作品同样可以渗透出时代的气息。进入二十世纪五十年代以后，随着社会环境丕变，其作品也有所表现。他曾说"花鸟画要画得朝气蓬勃，使人乍后如亲临其境，如欣赏鲜花和活泼的虫鸟一样，消除掉一天的疲荣，更感生活幸福。"这种"朝气蓬勃"的表现手法最明显见于五十年代中后期，他以工笔重彩填矿物颜料为地，以凸显反视画中景物的色调和质感。从以上几点可以看出，于非闇的作品融合了众家之长，得百家之法，因此，在于非闇的绘画作品中，我们应该首先确定的是于非闇扎实深厚的绘画功底。于非闇的《双钩竹雀图》，是一幅在民间收藏的作品。这幅画，构图严谨，用笔流畅，工笔用的线条、用墨线浓淡、粗细、虚实、轻重、刚柔、曲线表现的十分到位，先是出了于非闇所具有的扎实的中国画功底。正如中国著名书画大师杨仁恺所言，蓬莱于氏双钩“竹雀图”用笔老道雕嵌绿尤见清逸属佳作妙品。
于非闇的工笔双勾重彩花鸟画，主要吸收了三方面的营养。一是从古代绘画遗产中汲取传统精华。上文便是对其这一特点的描述。二是于非闇注重从写生中体察物理、物情、物态。三是于非闇不时借鉴民间绘画中优秀的技法。比如装饰风格、色彩的对比与协调。
在勾线用笔上则以书法入，表现出形象的气骨。于非闇反对过于工巧细密而失掉笔墨高韵和整体精神，作画不墨守成规，敢于创新。就笔法而言，他初以赵子固、陈老莲笔法为本，兼得圆硬尖瘦之趣，后以赵佶瘦金书笔法入画，笔道有了粗细、软硬、顿挫，波磔的变化，不仅书意大增，且使线条具有表现质感、体积感、空间感的丰富变化。对于工笔花鸟画来说，能否很好地描绘出树木的枝干如同勾线设色一样，都是检验一个工笔画画家技能水平高低的重要参照。在工笔画中，如果把处于次要位置的枝干刻画得过于细致精到，虽然形象逼真，但在整体效果中就会显得喧宾夺主，影响主题。如果把枝与干的形态弱化，忽略它的存在，即使是突出主题，但对于画面本身就会缺乏协调，整体效果不够统一。有的画家之所以用写意的方式在工笔画中表现枝干，就是回避了这方面的欠缺。
于非闇的《木笔山鹧图》，小枝与主干之间不仅在穿插避让上井然有序，主次关系明确，表现技巧也更生动自然。主干的线条虽然粗犷却不显粗糙，笔势稳重结实，细致的皴擦使枝干具有很强的立体效果，再加上淡赭色的渲染，很有些西画的韵味。盛开的辛夷花娇柔轻灵，给人以恬淡宁静、端庄秀丽、平和安详之感。层层晕染的花瓣丰满滋润，仿佛是由晶莹的玛瑙雕琢而成，那轻灵滋润的样子，让人心旷神怡。填色上于非闇主张柔婉鲜华，《祥云瑞鸽》写五只飞翔的瑞鸽。五只鸽子的羽毛颜色极尽变化之妙，而每一鸽子的羽毛又有不同。与祥云的色彩变幻颇为呼应。并且在整体构图上生动、精到，耐人寻味。
在于非闇的绘画作品中，宋人高古的气韵，精到的笔法与色彩的艳丽并不像冲突，不会因“艳”而显出“俗”，正是绘画大师的高明之处。所以艳美之色与高古之意，整体的贯穿在于非闇的作品之中的，是一格基调，也是识别其作品的根本。

In the dark from the age of 46 began to study painting, started late, but a great achievement. This and he had studied horticulture, birds, for later painting meticulous flower and bird laid the foundation. By 40s its reputation and Chang be roughly the same. He studied fine brushwork flower and bird painting, starting from the study of Chen Hongshou in the Qing Dynasty, after song and Yuan painting, and to study the Zhao Ji method. During the work of antiquities, exposed to a lot of paintings, broaden their horizons, improve the painting art. Division of ancient painting stands and not imitation, heavier nature. Grass can reproduce the dynamic characteristics, and still not like the stiff. In addition to study and learn Song Chunsi scroll paintings, ancient decoration. The hook line pen on the absorption of calligraphy method, color advocate soft fresh China, showing the air bone image. Too fine and close against the lost high and the overall spirit of ink rhyme. Painting not legalistic, dare to innovate. Baimiao orchid and bamboo Narcissus, vivid, elegant Seiitsu, painted peony will spring flowers, autumn Xia Zhiye, in a dry extract. From reality and above reality, to coincide with nature. The calligraphy for the skinny body, and good at making.
In the dark the artistic features can be learned from the teacher-student relationship on. Chen Hongshou's great influence on non darkness. Chen Hongshou, word chapter Hou, number old lotus. Zhuji (now Zhejiang, Zhuji). Is proud and arrogant stubborn, when students called Chongzhen, Neiting worship, not; after the fall of the Ming Qing, in Zhejiang, the monk, no regret later, old later. Good poetry, work calligraphy, longer than painting. Good characters, landscapes, flowers and birds, such as bamboo, is famous for its fine brushwork figure. The painting trunk lines of clothes Jin Wei, fine clear circle, in his late years, the image is exaggerated, or abnormal bizarre personality. Flowers and birds painted fine, rich colors Qingli, decoration. Also can draw freehand brushwork of flowers, fully and delightfully. Is also more than literary works for illustrations, can show the original character of the spiritual temperament. The painting style concise, color pigmentation subtle, ancient style, the famous painting, with the North Cui Zizhong and said "South North Cui chen". And Chen Hongshou also imitate the Wulin school Lan Ying and Li Gonglin in the song dynasty. Lan Ying painted landscape, and odd style show to run. Set two Jin and Tang, song, Yuan Dynasty calligraphy and other times not long. Its style is changed from the aspects of the generation. In his works gradually vigorous and sparse dang. The style also has various aspects, some subtle p.e.e.r ink works, some works of green heavy color painting is exquisite, gorgeous colors, more and more old. In his writing interests quite vigorous, Shen Zhou. He and figures, flowers and birds, orchid and bamboo, all the ancient samadhi. Li Gonglin, Zibo, Anhui, Tongcheng, learned to, painting diversity, comprehensive technology, not only in the pommel horse, immortal Buddha figure, also can do some landscape, flower and bird. The establishment of the "line drawing" painting creation form.

In the dark about the age of 46 began painting meticulous painting, starting from the study of Chen Hongshou in the Qing Dynasty, after song and Yuan painting, and to study the Zhao Ji method. Its weight is a major feature in the case, he is in the last year of life, ill made a "magpie" willow, wrote in comments: "from the five generation to the two Song Chen Lin is my learning traditional first stage, experts Zhao Ji is the second stage, since then I have some knowledge in the garden sketch, and draw on folk painting, but the operating position of literati painting also never neglect. So hard until today, deeply appreciate life is the source of creation, makeup, makeup and all white clothing performance skills are this also." This is an important summary of his lifetime art mileage. But the division of the ancient and not imitation, a two song double hook techniques, since the school. The composition of break stereotypes, pen for coloring gorgeous but not vulgar move among force and soft. Picturesque peony, take the flowers of spring, Xia Zhiye, autumn dry, both distant view, but also near reward. And a good poem in the painting postscript, with self engraved seal, so that the screen full of charm. He Yifeng rigorous, have a lesson, not a little. During the work of antiquities, exposed to a lot of paintings, and often appear in the antique shop, by copying paintings draw many techniques. Also to Beijing the Imperial Palace research works, broaden their horizons, improve the painting art. Shenyang the Imperial Palace copy Huang Quan "sketch map) and rare Zhao Ji" Rui map ", inherit the tradition of realism. In addition to study and learn Song Chunsi scroll paintings, ancient decoration.
In the dark of the flower and bird not only Li Gonglin's brushwork, Lan Ying of various style, embodies Chen Hongshou's ancient wit. "Imitation and bird" expells Yubi in real profile. In particular, the brightly colored birds, slightly upward moment, extremely naive antiquity, most can convey the painting. On this basis, non dark paintings can also penetrate the flavor of the times. After entering 1950s, along with the social environment has greatly changed, his works have also been shown. He said the "flower and bird painting to draw the first after full of youthful spirit, such as flowers and lively personally visit, such as birds and insects, eliminate the day fatigue life more sense of honor, happiness. "This" the most obvious expression full of youthful spirit "in late 50s, he filled the mineral pigment to meticulous is, to highlight the reverse painting scenery tone and texture. Can be seen from the above points, in the dark the work is a fusion of many long, have hundreds of law, therefore, is non dark painting works, we should first make sure that is in the dark and deep drawing skills. In the dark of the hook "bamboo bird map", is a collection of works in the folk. This painting, rigorous composition, smooth pen, with fine lines, with black shade, thickness, strength, weight, hardness, performance curve is in place, the first is out in the dark with solid China painting skills. As China famous painting master Yang Renkai said, Penglai's "bamboo bird map" pen hook road carved inlay in particular see Seiitsu is a masterpiece of green.
In the dark of the fine brushwork flower and bird painting color double hook, mainly in three areas to absorb the nutrition. First, draw the traditional essence from the ancient painting heritage. Above is a description of this characteristic. The two is in the dark on the show from the physical situation, and painting in the state. Three is in the dark from time to time draw lessons from folk painting excellent techniques. Such as decorative style, color contrast and coordination.
In line with the hook pen calligraphy to show the image of the bone, gas. In the dark is too dense and fine against the lost and the overall high ink rhyme painting spirit, not rigid, dare to innovate. On writing, he first by Zhao Zigu, Chen Laolian strokes for this, both hard and sharp thin circle of interest, with Zhao Ji thin gold book style painting, pen with the thickness, hardness, cadence, change zhe wave, not only intended to increase, and the lines with a rich variety of texture, volume the sense of space. For Chinese painting, can well depict the branches of the trees like the hook line design, is an important reference to test a painter painting skill level. In the painting, if put in a secondary position branches depict too detailed subtlety, although vivid, but will be in the overall effect is overwhelming, the impact of the theme. If the branches and dry form weakened, ignoring its existence, even if the prominent theme, but the screen itself will lack coordination, the overall effect is not uniform. Some artists are using freehand way branches in painting, is avoided in the gaps.
In the dark of the "Magnolia Hill Partridge map", and not only in the trunk between branchlets interspersed with avoidance in order, clear the relationship between primary and secondary, performance skills are also more vivid and natural. Trunk lines although rough but not rough, because of steady strong, careful cunca to branch has strong stereo effect, plus ochroleucus rendering, some western flavor. Blooming magnolia flower feminine ethereal, gives a quiet, dignified and beautiful, peaceful and quiet feeling. The layers of blooming petals plump moist, as if by crystal agate carved the ethereal moist appearance, refreshing. In the Dark Lord Rouwan coloring Zhang Hua Xian, "auspicious clouds" write five flying pigeon pigeon rui. Five dove feather color range ", and every dove feather is different. And the color changes are echoed auspicious clouds. And the composition of vivid and subtlety, thought provoking.