The textual function(textual meta-function)is one of the three meta-functions of Systemic Functional Grammar,which refers to the fact that people use language to express how to organize information,making the information as a whole based on semantic coherence.This text departs from the textual function,which includes thematic structure,information structure and cohesion,through the analysis of Du Fu’s“Mooring a Night”and its translation,the author aims to illustrate the analysis of the textual function in the process of the translation from the perspective of thematic structure and cohesion.