Ras-associated domain family 1A (RASSF1A) genes are members of the RASSF family, which bind to Ras in a guanosine triphosphate(GTP)-dependent manner and then induce Ras-mediated apoptosis. The protein encoded by the RASSF1A gene is similar to the Ras effector protein, which can interact with DNA repair protein XPA, and can also inhibit the accumulation of cyclin D1, thereby inducing cell cycle arrest. The deletion or abnormal expression of RASSF1A gene is related to the pathogenesis of various malignant tumors, indicating that it has tumor suppressor function. RASSF1A gene methylation has been found in at least 37 tumors, and RASSF1A gene may be the most frequently described methylated gene in human cancers. In this paper, the abnormal methylation of RASSF1A gene in different malignant tumors was introduced, and the research progress of its related effects and mechanisms in malignant tumors of the respiratory system, digestive system, genitourinary system, and nervous system in recent years was reviewed, with a view to malignant tumors early diagnosis, individual molecular targeted therapy and prognostic evaluation provide important guidance.