U2 small ribonucleoprotein（snRNP）is a kind of splicing body that plays a key role in the process of human nuclear splicing. The maturation of mRNA，including the processing，splicing and transport of 5′ and 3′ ends，is closely related to U2 snRNP. The intron branching site sequence is identified by U2 snRNP in splice assembly. U2 snRNP maintains the transcription of essential repair factors in the body. In addition，it can prevent the transcriptional site from forming R-loop structure and directly promote DNA repair. Studies have shown that U2 snRNP exists in a variety of human cancer tissues，and its main feature is the mutation of its core component gene and the increased expression level of core component. These changes further affect the migration，proliferation， invasion and other cellular behaviors of tumor cells，and are the key factors in the occurrence and development of tumor. In view of the molecular regulatory role of U2 snRNP in tumors，it is expected to become a new target for clinical diagnosis，treatment and drug therapy. The purpose of this article is to comprehensively review the mechanism of U2 snRNP in cancer.