Abstract: This paper takes the expression format: "A is good, B as well" as research object and studies its syntactic function and the semantic relations between "A" and "B" as well as the semantic relation with the later part through the analysis of corpus. It is showed that the format "A is good, B as well" is mainly used to state a fact, or express concessions, discontent, yes or no, adding a certain mood or modality to the sentence, thus enhances the expressing and communication