Objective: To observe the influence of aquaporin 9 (AQP9) on migratory ability in liver cancer HepG2 cells through induction of its expression by oleic acid. Methods: In HepG2 cells following different treatment (treatment of 0, 250, and 500 μmol/L oleic acid, or treatment of AgNO3+500 μmol/L oleic acid), the AQP9 protein expression was determined by Western blot analysis and cellular migratory ability was measured by scratch assay, respectively. Results: After oleic acid treatment, the AQP9 protein expression was significantly up-regulated in HepG2 cells, and their migratory ability was significantly increased, which all presented a concentration-dependent manner (all P<0.05), while, these effects of oleic acid were abolished by pretreatment of the aquaporin inhibitor AgNO3. Conclusion: The migratory ability of liver cancer HepG2 cells is associated with the AQP9 expression, which is the higher the AQP9 expression, the stronger the migratory ability of the HepG2 cells.