Objective To explore the effects and mechanism of ursolic acid ( UA) on cholesterol metabolism in human hepatocellular carcinoma HepG2 and mouse hepatocyte AML-12. Methods HepG2 and AML-12 cells were treated with different concentrations of UA (0,10,20,40 μmol·L-1)for 24 h, then the mRNA and protein expression of cholesterol 7alpha-hydroxylase (CYP7A1) and intracellular cholesterol level was detected by RT-PCR、Western blotting and enzymatic method, respectively. Results Compared with 0 μmol·L-1 UA, 20 μmol·L-1 and 40 μmol·L-1 UA significantly increased the expressions of CYP7A1 mRNA and protein(P<0. 05), and decreased intracellular cholesterol level in HepG2 and AML-12 cells (P<0. 05). Conclusion A certain concentration of UA can reduce the level of cholesterol in HepG2 and AML-12 cells. CYP7A1 may be involved in the regulation process.