Hepatitis B virus X protein (HBx) is involved in the initiation and progression of hepatocellular carcinoma (HCC). However, the mechanism is still needed to be elucidated. In this study, we explored the relationship between HBx and microRNA and their roles in hepato-carcinogenesis. Firstly, by global microarray-based microRNA profiling and qRT-PCR, we found miR-181a was strongly up-regulated in HepG2.2.15 cells (HBV positive) and pHBV1.3-expressing HepG2 cells, and HBx played a major role in it. Secondly, reduced PTEN protein expression in the presence of HBx was aslo mediated by miR-181a, and in the Luciferase reporter system, miR-181a inhibited the PTEN translation by binding the PTEN 3'-untranslated-region (UTR), and PTEN protein was decreased when epigenetic expression of miR-181a and rescued by knocking down miR-181a. Finally, HBx interrupted the balance between apoptosis and proliferation, which contributed to the development of hepatocellular carcinoma, was also related to the interaction of miR-181a and PTEN. Taken together, we presented here a novel cross-talk between miR-181a and PTEN which was raised by HBx, and this shined a new line in HBV-related hepato-carcinogenesis.