A text is the carrier of language,and the foundation of cognizing and distinguishing its styles and functions.Text typology offers TQA objective and theoretical underpinnings.Classification and cognition of text types is a fundamental and cognitive approach to text types and has the original guiding effects on TQA.Different text types are meant not only to make up different writing forms including lexical features,styles and norms of writing,rhetorical devices,etc,but also to form different language functions,different text focuses,different TT purposes and translation methods.Obviously,these differences require us to establish different assessment criteria and principles,which provide us with TQA references,and lend themselves to further explore and study TQA model so as to make it maneuverable and practical.