Abstract: Objective To explore the therapeutic efficacy and the mechanism of magnesium isoglycyrrhizinate on rats with non acoholic steatohepatitis.Methods A total of 50 male Srague Dawley rats were randomly assigned into 5 groups.The rats in the control(N) group were fed with common food,the model I(M1) group and model II(M2) groups were fed with high-fat diets,the treatment group(T1) rats were treated with magnesium isoglycyrrhizinate and dietary therapy group(T2) rats were fed with high-fat diets until 12 weeks.The T2 group rats were then treated with common food and the rats in T1 group were treated with magnesium isoglycyrrhizinate(120mg·kg-1·d-1).The rats in N and M1 group were killed at the end of the12th week and while the ones in M2,T1 and T2 group at the end of the 16th week.Liver function tests(AST and ALT),lipid metabolism(TC,TG,HDL and LDL-C) and lipid peroxidation(MDA,SOD and GSH) parameters were measured and histopathological changes of liver were observed.Results The rats in M1 group developed NASH after 12 weeks.The rats in the N group had aggravated hepatic fatty degeneration and inflammation,increased TC,TG,LDL-C and MDA,and decreased HDL,SOD and GSH compared to the control group(P<0.05).The degree of NASH aggravated,and the AST and ALT levels were increased after week 16 in the M2 group(P<0.05).The parameters and the degree of severity of hepatic fat degeneration in T1 group were all improved compared to the M1 and M2 groups(P<0.05).But there was no significant change in the T1 group(P>0.05).Conclusion Magnesium isoglycyrrhizinate therapy can improve lipid metabolism disorder,anti-lipid peroxidation,and anti-inflammation in patients with non acoholic steatohepatitis.