The first part of the paper is introduction, which introduces the problems we are facing in English teaching and the content of the research as well as the significance of it. The second part is literal review, which introduces lexical cohesion theories by some foreign and Chinese specialists and empirical studies on lexical cohesion devices.The third part is research methodology, which describes the methods adopted in the paper and the measurements of the research. The Forth part is results and discussion, which analyzes the results and makes a comparison. The following parts are conclusion, acknowledgments, references as well as appendixes, which make a conclusion and demonstration to this paper.