在采用应力－强度干涉理论进行可靠性分析时，需要根据材料的现有疲劳实验数据，获得任意指定寿命下的疲劳强度概率分布．文中提出了一种疲劳寿命服从对数正态分布的疲劳强度概率分布数值模拟方法．该方法在有限寿命阶段内，根据两条已知的疲劳特性( P- S- N) 曲线，重构任意存活率下的 P- S- N 曲线，进而运用蒙特卡罗技术推断任意指定寿命下的疲劳强度概率分布．以20Cr2Ni4A 为例进行相关分析，结果表明，P- S- N 曲线重构精度高，疲劳强度概率分布接受正态分布假设，模拟结果符合等同性原理和疲劳强度衰减理论．这说明文中方法是有效的．

When a reliability analysis is performed according to the stress- strength interference theory,the fatiguestrength probability distribution needs to be obtained at an arbitrary fatigue life based on the existing fatigue experi-ment data of material.In this paper,a simulation method of fatigue strength probability distribution is proposedunder the condition that the fatigue life follows a lognormal distribution.In this method,a P- S- N curve at an arbi-trary survival probability with a finite life is reconstructed according to two known P- S- N curves,and then thefatigue strength probability distribution at an arbitrary fatigue life is inferred by means of the Monte Carlo simulationmethod.Finally,analyses on 20Cr2Ni4A are performed.It is found that the reconstructed P- S- N curve is highlyprecise,the fatigue strength probability distribution follows normal distribution and the simulation results accordwell with the equality principle and the fatigue strength degradation theory.The above results show that the pro-posed method is effective.