Duanzuo(断做) is a rhetorical category of eight-part essay opposite to Daishuo(代说). We can identify its rationality in logic and variability in dialectics from the transformation of Duanzuo, which was originally complementary to Daishuo and later became the presentation of the author's subjectivity, and the change of Duanzuo from the confrontation of Narration to the heretic “Linglie(凌躐)”. From the connotation circumscription and variation of “Duanzuo” in the rhetoric category, we can locate the development and evolution of the writing rules, rhetoric methods and aesthetic orientation during the Ming and Qing dynasty. Thus, it is a miniature of the history of the eight-part essay of the Ming and Qing dynasty.