Abstract: Objective: to evaluate the effect of Olprinone on the contractility of fatigued diaphragms in rats induced by cecal ligation and puncture（CLP）. Methods: Rats were divided into four groups of 10 each. In group Ⅰ, the rats were only performed with artificial operation. In group Ⅱ, Ⅲ, Ⅳ, diaphragmatic fatigue was induced by CLP. Olprinone were injected into abdomen cavity with the dose of 10mg/kg or 20mg/kg in group Ⅲ and Ⅳ. During the experiment, the diaphragmatic muscles were first stimulated by the electric at 10Hz, 20Hz, 50Hz, 100Hz（6V, continues 1s） and the contractility was detected; then the diaphragmatic muscles were stimulated by single stimulation with 6V current continuing 2ms and the Peak Twitch Tensicn（PTT）, Time to Peak Tension（TPT）, Half relaxation time（1/2RT） were detected. Results: compared with artificial operation group, the contractility of the other three groups were decreased obviously （P＜0.05）; but there were no difference between the fatigued diaphragms induced by CLP with or without pre-treating with Olprinone（P＞0.05）. Also there were no difference in TPT and 1/2RT induced by 6V, 2ms single electric stimulation among all these four groups （P＞0.05）. conclusion:fatigued diaphragms could be induced by bacterial peritonitis, but pre-treating with single abdomen cavity injection Olprinone cannot relieve the rat diaphragmatic fatigability induced by CLP.