出生于江苏常熟，在民国13年（1924年）毕业于苏州美术专科学校。此后毕生在上海工作。他的艺术生涯跨越了20世纪20至50年代，期间他曾担任苏州美专沪校副校长，同时参与创立了上海水彩画研究会和上海粉画学会，并分别担任会长。
李咏森是中国水彩画的拓荒者，他以清新的风格和细腻高雅的写实技巧，将中西绘画技巧熔为一炉。他的画作以“用水调和颜色绘制的图画”为基础，融入了中国画的气韵、传神、意境创造等元素。他的用笔爽快而深邃，用色透明而清丽，特别擅长表现花卉景物和风景。他注重骨法用笔，不涂不改，点染成法，层次丰富。
Born in Changshu, Jiangsu, he graduated from Suzhou Fine Arts College in 1924. He has worked in Shanghai all his life since then. His artistic career spanned the 1920s to the 1950s, during which he served as vice president of Suzhou Fine Arts College Shanghai School, and participated in the establishment of Shanghai Watercolor Research Society and Shanghai Pastel Painting Society, and served as president respectively.
Li Yongsen is a pioneer of Chinese watercolor painting. With his fresh style and delicate and elegant realistic techniques, he has integrated Chinese and Western painting techniques. His paintings are based on "pictures painted with water and colors", and incorporate elements of Chinese painting such as the charm, vividness, and artistic conception creation. His brushwork is refreshing and profound, and his colors are transparent and beautiful. He is particularly good at expressing flowers and landscapes. He pays attention to the bone method of brushwork, does not smear or change, and the method of dotting and dyeing is rich in layers.
