TMEM16A plays an important role in cell proliferation in various cancers. However, less was known about the expression and role of TMEM16A in hepatocellular carcinoma. We screened the expression of TMEM16A in patients' hepatocellular carcinoma tissues, and also analyzed the biological function of hepatocellular carcinoma cells by knockdown of TMEM16A, as well as the expression of MAPK signaling proteins, including p38, p-p38, ERK1/2, p-ERK1/2, JNK, and p-JNK, and cell cycle regulatory protein cyclin D1 in TMEM16A siRNA-transfected SMMC-7721 cells by Western blot. Our results showed that TMEM16A was overexpressed in hepatocellular carcinoma tissues. Inhibition of TMEM16A suppressed the cell proliferation, migration, and invasion, and cell cycle progression but did not influence the cell apoptosis. TMEM16A siRNA-suppressed cancer cell proliferation and tumor growth were accompanied by a reduction of p38 and ERK1/2 activation and cyclin D1 induction, and were not influenced by other tested MAPK signaling proteins. In addition, inhibition of TMEM16A suppressed tumorigenicity in vivo. TMEM16A is overexpressed in hepatocellular carcinoma, and that inhibition of TMEM16A suppressed MAPK and growth of hepatocellular carcinoma. TMEM16A could be a potentially novel therapeutic target for human cancers, including hepatocellular carcinoma.