Text theory is an important theory in the cognitive poetics. Text analysis is a dynamic process by using the threelevel classification of the discourse world, text world, and the subworld of a text, the writer, text and reader are closely combined. In text theory, the text is the analysis object. Based on the consideration of the author, the reader makes different construes with the text information and experiences, and constructs different cognitive world to interpret the text. This essay uses the text world theory to illustrate the causes for the theme diversity with a unified view. It proves that the text theory has a strong explanation for the construction of the text meaning, and reveals that the interpretation of literary text is not closed.