Zhang Daqian's Picture of Flat Peach Offering Birthday is a rather solemn birthday painting by Zhang Daqian at the beginning of 1945. During this period, Zhang Daqian's paintings of ladies drew lessons from Dunhuang very obviously. He uses smooth and changeable lines to express objects, and the colors are mixed with solid colors, which are calm, bright and harmonious. Most of the pattern combinations on women's clothes are taken from the decorative patterns in Dunhuang paintings. Zhang Daqian absorbed nutrition extensively from ancient paintings and formed his own characteristics. Another special feature of this painting is that "Zhang Yu fills the skirt" is marked on the lower left. He is the son of Zhang Wenxiu, the fourth brother of Daqian. Daqian stayed in Dunhuang for several years, and Zhang Yu has always been his best assistant. In the murals copied by Zhang Daqian in Dunhuang, the main parts, such as Buddha statues, are sketched and colored by himself, and the names of collaborators will be indicated when writing the paintings. Therefore, there is Zhang Yuzhi's inscription and seal, which not only follows the old Dunhuang system, but also shows my nephew's talent, which is also rare in Daqian paintings