Abstract: Radiation pneumonitis is a severe complication of irradiation.In order to improve the treatment efficiency,we used the compound anisodine （CA） to prevent aud treat the radiation pneumonitis in rats.45 wistar rats were randomly divided into three groups: （1） irradiation group,（2） CA-treated group,（3）control group.The thoraces of rats in irradiation and CA-treated group were exposed to 30 Gy single exposure dose of ⁶⁰Coγ radiation.2 days before irradiation the rats of CA-treated group were injected with CA sc.per day,while the other groups were injected 0.9% saline sc.until they were sacrificed on 15, 30, 45 days respectively.The pathological morphology showed:the rats in irradiation group presented typical radiation pneumonitis while the rats in CA-treated group,their lungs showed only slight radiation reaction and recovered soon.The experimental results indicate that in the early stage,treatment and prevention of radiation pneumonitis in rats with CA is effective.