Sutizi (vulgar style script) refers to popular scripts that are prevalent among folk people but against the written styles during different periods. In opposition to Sutizi is Zhengtizi (standard style script).

After Chinese characters developed into Zhuanwen (seal script), character components became relatively fixed after the overall straightening; when they developed from Zhuanwen into Lishu (official script) and then Kaishu (regular script), the shape of character components was further fixed; in this way, the way of writing Chinese characters had its own rule. Characters that conform to the rule were Zhengtizi, while those go against the rule were Sutizi.

Compared with Zhengtizi, Sutizi wais characterized by change of strokes or replace of character components, and some Sutizi are coinages. Because many Sutizi had fewer strokes than Zhengtizi, and were more convenient to use, they were handed down from history, and some of them were used as simplified characters to replace the original complicated characters during the simplification of Chinese characters in the history.

Many Sutizi appeared in tablets of the past dynasties, which even influenced famous calligraphers. Sutizi was also often seen in the rubber stamps of dramas and novels in the Song Dynasty (960-1279), and many of these characters are even in use today. The Simplification Plan of Chinese Characters, published in 1955, authorized some Sutizi as regular scripts, and at the same time abolished a great many Sutizi, which played an active role in standardization of Chinese characters. In this way, Sutizi has less opportunity to appear in formal occasions.