Within the theoretical framework of functional linguistics, this paper explores the relativity between the language features of discourse in Chinese medical clinic and the humanistic thought of Chinese medicine. The expression of mental process shows the patient-centered concept of the humanistic thought of Chinese medicine, while the exploiting of lexical metaphor proves that Chinese medicine takes deep root in traditional culture. In addition, this study discusses the social communicative function that grammatical metaphor performs in clinic discourse. It is feasible to investigate this type of discourse from the perspective of functional linguistics. Functional linguistics provides insight in the study of clinic discourse.