从缸盖本体取样测试了其材料疲劳性能，提出了一种新的疲劳寿命分布模型选用方法，高应力低寿命区选用对数正态分布模型，低应力长寿命区选用三参数威布尔分布模型。给出了用Matlab计算三参数幂函数S-N模型参数的方法，并分析了不同S-N疲劳应力寿命模型拟合偏差，结果表明，三参数幂函数模型精度明显优于另外两种。最后根据计算结果拟合预测了疲劳强度，混合分布预测结果与升降法测试结果的偏差最小，为6 MPa。

The fatigue performance of cylinder head material was tested based on the sample extracted from the cylinder head. A new selection method of fatigue life distribution model was proposed. Lognormal distribution model was adopted in high stress and low cycle life zone. Three parameter Weibull distribution model was adopted in low stress and high cycle life zone. MATLAB calculating parameter method of three parameter power function S-N model was given and the fitting errors of different S-N fatigue stress life models were analyzed. The results showed that the accuracy of three parameter power function model was better than the other two models. Finally, the fatigue strength was predicted according to the calculation results. The smallest deviation between predicted result of hybrid life model and test result of up-and-down test was 6 MPa.