As we all know, righteousness, textual research and rhetoric are the terms of the trinity academic papers of Tongcheng School. Yao Nai first systematically put forward and expounded the viewpoint of the unity of righteousness, textual research and articles, and set up the program and banner of Tongcheng School's literary theory. The unity of meaning, examination and diction contains three meanings: first, as a part of "learning" and "writing" (A Theory of Writing and Learning, Yao Nai's Preface to Poetry), the three have their own needs and values, which cannot be neglected; Second, the three should absorb each other, complement each other, enrich and improve each other; Thirdly, the relationship between the three is hierarchical, that is, "the righteousness is in the line, then the text is attached, and the textual research is returned" (Wang Xianqian's Preface to Continuing Ancient Documents).