Form is an important marker of a rhetorical device. In using them,people often change the form of the rhetorical devices according their need. The change in the form is called the variation. When we appreciate the literature works we can find some clue to the author's artistic conception from the variation of rhetorical devices so as to deepen our understanding of the literature works and improve our ability of appreciation. The study of the variation of rhetorical devices is helpful for us to track the development of rhetorical devices.