Objective To observe the effects of Yushen Heji on expressions of Heme Oxygenase (HO-1) and HO-2 in kidney of diabetic rats;To explore its mechanism in diabetic nephropathy. Methods SD rats were randomly divided into normal group, model group, control group and treatment group. Models were duplicated by subcutaneous injection STZ. Control group and treatment group were given gavage with related medicine, while normal group and model group were given gavage with the same amount of distilled water. Eight weeks later, the urine of rats was collected to detect the 24 h Upro and Ucr;the rats were sacrificed to detect the levels of CO, BUN and Scr;the kidneys were harvested for observing the expressions of HO-1 and HO-2 by immunohistochemistry.Results Compared with normal group, the contents of BUN, 24 h Upro and Scr all increased in model group;Ccr and plasma CO decreased;the expressions of HO-1 and HO-2 in kidney tissues were obviously reduced (P<0.01). Compared with model group, the contents of BUN, 24 h Upro and Scr all obviously decreased in treatment group and control group;Ccr and plasma CO increased;the expressions of HO-1 and HO-2 in kidney tissues obviously increased (P<0.05,P<0.01). Compared with control group, the contents of 24 h Upro decreased in treatment group;plasma CO increased;the expressions of HO-1 and HO-2 in kidney tissues obviously increased (P<0.05,P<0.01).Conclusion Yushen Heji has therapeutic effect on diabetic nephropathy rats, which may related with HO/CO system.