为获得安全可靠的疲劳极限,提出了处理升降法试验数据置信限-可靠度-应力(C-R-S)曲线方法.把升降法的应力水平和可靠度作为随机变量,进行了最优分布检验和参数估计,确定置信限,按三参数Weibull分布、采用最小二乘法拟合C-R-S曲线,获得具有一定置信限和可靠度的疲劳极限.通过38SiMnMo调质齿轮弯曲疲劳强度升降法试验,获得置信限为95%、可靠度为99%的弯曲疲劳极限应力为283.76MPa,位于GB3480极限应力框图内,表明该方法是可行的. In order to obtain a safe and reliable fatigue limit, a confidence-limit-reliability-stress (CRS) curve method is proposed to deal with the test data of the lifting and lowering method. The stress distribution and reliability of the lifting and lowering method are regarded as the random variables, and the optimal distribution test and parameter estimation , To determine the confidence limit, according to the three-parameter Weibull distribution, the least squares method to fit the CRS curve to obtain a certain confidence limit and reliability of the fatigue limit by 38SiMnMo quenching and tempering gear fatigue strength test method to obtain a confidence limit of 95% , The ultimate fatigue strength of bending fatigue of 99% is 283.76MPa, which is located in the GB3480 ultimate stress diagram, which shows that this method is feasible.