Official script is also called "Assistant Book" and "Historical Book". Official script evolved from the simplification of seal script, changing the round strokes of seal script into square folds, and changing the structure from pictograms to strokes to facilitate writing. It was founded in the Qin Dynasty and was commonly used in the Han and Wei Dynasties. There are two types of official script. One is Qin Li and the other is Han Li. Qin Li is also called Gu Li. Jin Weiheng's "Four Types of Calligraphy" records: "Since Qin used seal script, there were many things to do, and it was difficult to write seal characters, so it ordered the official to assist the calligraphy, which is called Li Zi." Cheng Miao organized this calligraphy style at that time, and later generations had it Cheng Miao created the official script legend. The writing system of the Qin Dynasty was originally seal script, but due to the large number of memorials, it was difficult to write in seal script. Therefore, when the officials were sorting out documents, they came up with an emergency font called official script. "The official script is the fastest way to write the seal script." That is to say, the official script is the shorthand way of writing the small seal script. That is to say, the arc-shaped lines of the small seal script are turned into square, folded and straight lines, which to a certain extent realizes the symbolization of Chinese characters and the meaning of the era of strokes. Oracle bone inscriptions, bronze inscriptions, and seal script all belong to the category of ancient writing, while official script and regular script belong to the category of modern writing. Han Li, also known as Jin Li, was developed on the basis of Qin Li and matured around the middle of the Western Han Dynasty. The Han official scripts we see now are mainly stone carvings, and there are also some wooden slips. The main difference between the Han Li and the Qin Li is that the Qin Li's strokes are straight and square, while the Han Li's strokes, strokes and long horizontal strokes are wavy.