Abstract: Objective: To study the effect of taurine on cholesterol degradation and its preliminary mechanism.Methods: Hep G2 cells were treated with 1,10,and 20 mmol / L taurine for 48 h after being cultured in DMEM supplemented with 0.02 mmol / L cholesterol. Then the levels of intracellular total cholesterol( TC),free cholesterol( FC),ester cholesterol( EC),total bile acids( TBAc) and medium TBA( TBAm) were determined.The expression of CYP7A1 and its regulatory key molecules were detected by western blot after Hep G2 cells were incubated with20 mmol / L taurine for 24 h.Results: TC,FC and EC were significantly reduced and TBAc and TBAm were increased by 10 mmol / L and 20 mmol / L taurine for 48 h- treatment( p < 0.05 or p < 0.01). The expression of CYP7A1 was significantly increased by 20 mmol / L taurine at 24 h( p < 0.05).The expression of MAPK,ERK,JNK,c- jun and p- c- jun were obviously decreased( p < 0.05) and the expression of HNF4α had no significant change by 20 mmol / L taurine for 24 h. Conclusion: Taurine can enhance CYP7A1 expression by inhibiting MAPK / JNK,MAPK / ERK and c- Jun / p- c- Jun expression,to promote the transformation of cholesterol to bile acid in liver cells.