Abstract: This paper explores the multi-functions of tense based on Systemic Functional Grammar.It is found that tense has three functions：ideational，interpersonal and textual.The ideational function of tense consists of experiential and logical function.Experiential function refers to that tense can express experience occurring in the past，at presentor in the future，and logical function is expressed through three types of relationship：hypotactic，paratactic and independent.The interpersonal function can be understood either in a broad or a narrow sense.In a broad sense，it construes interpersonal relationships among different participants；in a narrow sense，it expresses modality meaning on certain continuums.The textual function of tense means that a chain of tense is formed in a text，and this chain can be either dynamic or static.