OBJECTIVE: This study aimed to observe the effect of microRNA-7 on the proliferation and migration of human hepatocellular carcinoma cell line SMMC-7721 and its effect on epithelial-mesenchymal transition (EMT). PATIENTS AND METHODS: Eukaryotic expression vector pcDNA3.1(-)-pri-miR-7(p-miR-7) was used to instantaneously transfect human liver cancer cells of SMMC-7721 cells in vitro. The expression of microRNA-7 was detected by RT-qPCR. Western blot was used to detect the expression of EMT marker proteins E-cadherin, beta-catenin, N-cadherin and Vimentin. The proliferation of SMMC-7721 cells was detected by CCK-8 assay, and the invasion and migration ability of cells was detected by transwell assay. RESULTS: Compared with the normal group, the expressions of E-cadherin and beta-catenin in SMMC-7721 cells transfected with miR-7 were significantly increased (p<0.05), while the expressions of N-cadherin and Vimentin were significantly decreased (p<0.05). Meanwhile, the proliferation, invasion and migration ability of the cells were significantly weakened (p<0.05). CONCLUSIONS: The miR-7 can inhibit the proliferation and invasion of human hepatocellular carcinoma cell line SMMC-7721, and its mechanism may be related to upregulation of E-cadherin, beta-catenin protein, and downregulation of N-cadherin and Vimentin proteins.