〔Abstract〕 Objective To investigate the effects of MiR-34 a-5 p overexpression on malignant proliferation, invasion and tumor formation of hepatocellular carcinoma HepG2 cells. Methods The relationship between MiR-34 a-5 p and MET was detected by luciferase assay. MET pcDNA vector was constructed to overexpress MET, miR-34 a-5 p and PCDNA-MET were transfected into HepG2 alone or in combination, and the cells were randomly divided into 4 groups: Control group, mimic group, MET group and mimic+MET group for subsequent experiments. Cell proliferation was detected by clone formation method. Flow cytometry was used to detect apoptosis. Transwell detected cell invasion. Protein expression levels of Ki67, PCNA, Bax, Bcl-2 and Caspase-3 were detected by Western blot. Nude mice were randomly divided into Control group and mimic group to detect tumor volume change and tumor weight at 30 d, immunohistochemistry was used to detect Ki67 positive expression rate and TUNEL staining cell apoptosis. Results There was a direct targeting relationship between MiR-34 a-5 p and MET. Compared with the Control group, the cell clone formation rate of mimic group significantly reduced(P<0.05), the levels of Ki67 and PCNA protein significantly reduced(P<0.05), the apoptosis rate significantly increased(P<0.05), the ratio of Bax/Bcl-2 and cleaved caspase-3/caspase-3 significantly increased(P<0.05), and the number of invaded cells significantly reduced(P<0.05). In the MET group, the cell clonal formation rate significantly increased(P<0.05), the levels of Ki67 and PCNA significantly increased(P<0.05), the apoptosis rate significantly decreased(P<0.05), the Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios significantly decreased(P<0.05), and the number of invaded cells significantly increased(P<0.05). Compared with the MET group, mimic+MET group showed significantly lower cell clone formation rate(P<0.05), significantly lower Ki67 and PCNA protein levels(P<0.05), significantly higher apoptosis rate(P<0.05), significantly higher Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios(P<0.05), and significantly lower cell invasion number(P<0.05). In the tumor formation experiments of nude mice, compared with the Control group, the tumor volume of the group mimic significantly decreased at day 25 and 30(P<0.05), the weight of tumor tissue significantly decreased(P<0.05), the number of Ki67 positive cells significantly decreased(P<0.05), and the apoptosis rate of tumor tissue significantly increased(P<0.05). Conclusion miR-34 a-5 p overexpression inhibits MET, inhibits HepG2 proliferation, invasion and promotes cell apoptosis, and inhibits tumor growth of xenograft tumor in nude mice with HCC.