From the 1940s, Sun Qifeng began to study the famous Han Dynasty inscriptions such as Chen Shi, Zhang Qian, Cao Quan and Huashan, and made great efforts in structure and strokes. Later, after constant tempering, it can be said that it has reached the level of "Seiko". After the 1980s, his official script was free from vulgarity and self-reliance, and he paid great attention to horizontal exhibition, widening his left pen and right pen, making it spread to the left and right like the wings of a bird, which was quite flying. The brushwork is simple and vigorous, elegant and picturesque. Later, Sun Qifeng became interested in Han bamboo slips. At the beginning of the 20th century, with the development of archaeology, a large number of Han bamboo slips were unearthed. The words on bamboo slips are Chinese ink. Their writers are mostly lower-class literati or folk calligraphers, so they have diverse styles and a natural and simple ancient interest. Sun Qifeng preferred the Han bamboo slips unearthed in Juyan, Wuwei and Gangu, and made a very rational imitation and research on them. He said: "Bamboo slips are not written by calligraphers, and the good and the bad are mixed. You must choose the fat and the thin, and get the best from the rough. " "Picking the fat and choosing the thin" is Sun Qifeng's consistent practice of inheriting and drawing lessons from tradition. The result of "picking the fat and picking the thin" on the bamboo slips is plain, which blends the essence of nature with the tenderness of Gu Zhuo carved on the tablet, creating a new style with free and easy posture and rich style.