MicroRNAs (miRNAs) play a vital role in regulating tumor progression. Dysregulated miR-136 expression was linked to the development of various human cancers. In the present study, we investigated the expression and relationship of miR-136 and COX2 in hepatocellular carcinoma (HCC) using relevant experiments, involving CCK-8, Transwell assay, and luciferase reporter assay. We demonstrated that miR-136 expression is obviously decreased in HCC tissues and cells, and negatively correlated with the expression of COX2 mRNA. In vitro assay revealed that overexpression of miR-136 significantly changed the expression of proliferation- and metastasis-related proteins and inhibited the proliferation, migration, and invasion of HepG2 and Hep3B cells. Dual-luciferase reporter assay validated that the 3'-untranslated region (3'-UTR) of COX2 is a direct target of miR-136. Furthermore, COX2 siRNA partially enhanced the miR-136 overexpression-induced inhibitory effects. In conclusion, miR-136 was vital in the regulation of HCC cell proliferation and metastasis by targeting COX2. Thus, our findings provided novel evidence that miR-136 might be recommended as a potential target for the diagnosis and treatment of HCC patients.