Abstract: MicroRNA-34 (miR-34) cluster includes miR-34a, miR-34b and miR-34c, which are closely related to the normal development of human body and the maintenance of multiple organ functions. The expression of miR-34 is regulated by tumor suppressor gene p53 and long non-coding RNAs (lncRNAs). Its unbalanced expression will lead to the occurrence and development of a series of diseases. MiR-34 is closely related to tumorigenesis and development. It plays an anti-cancer role mainly by blocking cell cycle, inducing apoptosis and autophagy, inhibiting epithelial mesenchymal transformation, and preventing cell migration and invasion. There is new evidence that miR-34 also plays an important role in cardiac protection. The function of miR-34 mainly involves NF-κB, Notch and other signaling pathways. The regulation based on the expression of miR-34 is conducive to the control and prognosis of some diseases. miR-34 is a potential target for clinical diagnosis and treatment, and has broad clinical application prospects. Therefore, this paper reviews the function and application progress of miR-34 cluster to provide reference for follow-up research.