Shuo Wen Jie Zi (Explanation on Chinese Characters) is the first lexical work analyzing the shape of the characters and searching the source of characters systematically in ancient China, written by Xu Shen in the Eastern Han Dynasty (25-220) and completed in the first year (121) during the reign of Jianguang. The book laid the foundation for the lexical works in ancient China. There were originally 14 sections, together with one preface. The body of the book is written mainly in Xiaozhuan (lesser seal script), including 9,353 characters, 1,163 ancient and unique characters, and 133,441 words of annotations. Many amendments were made in the past dynasties and the present version was revised by Xu Xuan in the Song Dynasty (960-1279).

Compared with the compiling way from the Zhou Dynasty (11^th century - 256BC) and the Qin Dynasty (221-206BC) to the Han Dynasty (206BC-220AD), this book made great changes in the way of compiling dictionaries and created the way of arranging characters by radical parts, which amounted to 540 parts in total. Summarizing the former theory of Liu Shu (Six Ways of Character Formation), Xu Shen created the method to systematically explain characters, i.e. explaining the meaning first, analyzing the structure then, and marking the pronunciation at last. The way to analyze grapheme was unprecedented. Shuo Wen Jie Zi made great contribution to the study on ancient characters, ancient literature and ancient history.