Objective:To investigate the effects of miRNA145 combined with metformin on the proliferation of human HCT116 cancer cells. Methods:miRNA145 overexpression mediated by recombinant lentivirus was exployed in HCT116 cells. Cell proliferation assay by CCK-8 method was conducted to determine the roles of miRNA145 and/or metformin on the cancer cells. Western blot analysis was used to determine the expression levels of AMPK and mTOR proteins. Results:Both miRNA 145 and metformin can inhibit the cell proliferation of HCT116. The combination of miRNA 145 and metformin exerted a much stronger inhibitory effect on cell proliferation than any of the two. The activation level of AMPK was also higher by the combination,and the p-mTOR expression level was lower by the combination. Conclusion:miRNA145 and metformin can exert an anticancer effect synergistically.