Cancer has always been the major disease that threatens human life. For most cancer patients, metastasis is the ultimate cause of death. Therefore, tumor metastasis has a decisive influence on tumor therapy and prognosis and has become a new hot point in tumor studies. Thus, we should explore tumor metastasis suppressor genes for new targets and new drugs that can be used to inhibit tumor metastasis from a variety of targets. Tumor metastasis suppressor gene 1 (TMSG1), also known as LASS2, is a newly found tumor metastasis suppressor gene. Preliminary studies showed that it not only suppressed tumor growth but was closely related to tumor metastasis. In this review, we introduced TMSG1 gene by discussing the discovery of TMSG1 and the structure of its encoded protein, and commented on the possible mechanism of TMSG1 in tumor invasion and metastasis.