BACKGROUND: It has confirmed that angiotensin converting enzyme inhibitor benazepril can delay fibrosis of varied organs. However, whether benazepril has inhabited effect on peritoneal fibrosis in the process of peritoneal dialysis is poorly understood. OBJECTIVE: It is assumed that benazepril could inhabit peritoneal fibrosis of peritoneum with peritoneal dialysis, in addition, to compare the effect to other mehods. METHODS: All rats were randomly and evenly divided into 4 groups. There was no intervention in the control group; saline solution, and 20 mL 42.5 g/L Dianeal solution, was injected into rats in the saline solution and peritoneal dialysis groups; in the combination group, 20 mL 42.5 g/L Dianeal solution was injected combined with oral taken benazepril 20 mg/(kg·d). The intraperitoneal injection performed once a day, for 4 successive weeks. The ultrafiltration function was performed 4 weeks later. Meantime, Paraffin sections were cut and stained by Van Gieson to measure peritoneal thickness. RESULTS AND CONCLUSION: Two rats in the peritoneal dialysis group and 1 rat in the combination group were dead. The remained 37 rats were included in the final analysis. Compared to the control and saline solution groups, the ultrafiltration volume of the peritoneal dialysis and combination groups were obviously decreased (P_(all)< 0.05), especially notably decreased in the combination group (P< 0.05). Compared to the control group end saline solution groups, the peritoneal thickness was significantly elevated in the combination group, but not as much as in the peritoneal dialysis group (P < 0.05). In the long-term peritoneal dialysis rats, administration of benazepril can effectively protect the ultrofiltration function of peritoneum and delay the progression of peritoneal fibrosis.