Vocabulary teaching is essential in the teaching of Chinese language, either as a first or second language. This study employed systematic functional linguistics to analyse teaching discourses collected from two classes, and explored ways to improve the effectiveness of vocabulary teaching. The teacher-participants used a total of 206 teaching discourses in the classroom to explain 27 target words. The schematic structure, transitivity and conjunction were first analyzed, and subsequently further analyzed together with students’ involvement rate. It has been found that the classroom discourse of vocabulary teaching shares the features of expository discourse, being brief and concise. It thus recommends that teachers should adapt their teaching to students’ level of understanding in order to identify the appropriate core of vocabulary teaching for the class. To facilitate students’ knowledge absorption, they should use more enhancing clauses for explanation, and classify the words by themes so that words in the same categories can be explained at the same time.