Objective To explore mRNA and protein expression of PAl-1 in kidney tissue of mice with IgA nephropathy (IgAN) and the effects of YiShen Decoction. Methods The IgAN model was built by the method of oral intake of bovine serum albumin(BSA)together with the injection of staphylococcus enterotoxin B(SEB)through caudal vein. The mRNA expression of PAI-1 was measured by fluorescent quantitative polymerase chain reaction (FQ-PER)and the expression of PAI-1 protein was measured by immunohistochemistry. Results No significant difference of mRNA and protein expression of PAI-1 was found between the low concentration and high concentration Yishen Decoction group. But the secretion and mRNA expression of PAI-1 in the low and hiigh concentration Yishen Decoction group was decreased more than that in the IgAN model group. Conclusion The abnormal expression of PAI-1 mRNA and protein played an important role in the onset and development of IgAN. The TCM Yishen Decoction could reduce the abnormal expression of the mRNA and protein of PAI-1 in kidney tissue of mice with IgA nephropathy.