【Abstract】〓Objective〓To investigate the renoprotective effect of paricalcitol in rats with diabetic nephropathy (DN) and its mechanism. Methods〓DN model rats were established by intraperitoneal injection with streptozotocin (STZ). The DN rats were randomly divided into the paricalcitol group (group P) and DN group (group D). Healthy rats were chosen as healthy control (group N). Group P were treated with 04μg/kg paricalcitol t.i.w. Group D and group N were given equal amount of 1,2Propanediol by gavage. 24h urinary protein and serum biochemical indicators were examined after 12 weeks.ELISA methods were applied to detect the concentration change of renin in the kidney, urine levels of prostaglandin E 2 (PGE 2 ). Immunohistochemistry were applied to detect the protein of COX2 and nephrin.Results Compared with those of group N, 24h urinary protein，serum creatinine，renin ,PGE 2 and COX2 of D group and P group were markedly increased, and they were significantly higher in group D than that in group P (P<005). Compared with that of group N, the expression of nephrin in group D and group P was markedly decreased, and lower expression was found in group D (P<005). Conclusion〓Paricalcitol can significantly reduce the proteinuria in rats with diabetic nephropathy, which may be associated with downregulation of COX2, PGE 2 and renin expression, upregulate the protein expression of podocin of podocyte.