This paper makes a comparative study of the distribution of Grammatical Metaphor (GM) in English thesis abstracts by Chinese MA students and MA students with English as their tongue, and then analyzes the discourse functions of GM as used in Chinese MA students' thesis abstracts. The analysis shows that Chinese EFL learners used significantly less ideational GM than their counterpart, and their uses of interpersonal GM are similar to that of native speakers. The underuse of ideational GM reduces the expected abstractness and objectivity of abstracts. Further analyses show that Chinese learners have the problems of overusing faded GM, misusing semantic prosody and collocation of GM, and making certain functions of GM redundant, which possibly result from a lack of academic genre awareness and negative L1 transfer, and which have further bad effect on information organization, positioning, and stance.