Abstract: This study aims to discuss the therapeutic effect of magnesium isoglycyrrhizinate on hepatitis B virus(HBV)transgenic mouse and its effect on cellular immunity and liver inflammation. The changes of serum aspartate aminotransferase(AST)and alanine aminotransferase(ALT)activity, the difference of serum hepatitis B surface antigen(HBsAg), liver tissue HBsAg mRNA, and the pathological morphological changes of liver tissue were detected to investigate the hepatic inflammatory lesions and the efficacy of magnesium isoglycyrrhizinate in HBV transgenic mouse. Peripheral blood lymphocytes were classified by flow cytometry, and serum cytokines were detected by cytometric bead array(CBA)to explore the mechanism of magnesium isoglycyrrhizinate to reduce hepatic inflammatory lesions in HBV transgenic mouse. After grouping HBV transgenic mouse with serum transaminase activity and 35 days of continuous administration, serum transaminases level in magnesium isoglycyrrhizinate ［15 mg/(kg ·d)］ group was significantly lower than that in control group(P< 0. 05), serum HBsAg protein and liver tissue HBsAg mRNA increased with time, but there was no significant difference between the two groups. The main pathological changes of liver were liver cell swelling, necrosis and focal inflammatory cell infiltration, and the pathological changes of liver in magnesium isoglycyrrhizinate group were lighter than those in control group. The number of CD8⁺ cells in the blood of magnesium isoglycyrrhizinate group was significantly less than that in the control group(P< 0. 05)and the CD4⁺/CD8⁺ cell ratio was significantly higher than that in the control group(P< 0. 05). The content of inflammatory cytokines in serum of magnesium isoglycyrrhizinate group decreased significantly(P< 0. 05). Magnesium isoglycyrrhizinate can regulate the immune function of HBV transgenic mouse, decrease the infiltration of inflammatory cells in hepatic tissue and hepatocyte injury, but do not affect the expression of hepatocyte HBsAg.