Abstract: Reliability study of fatigue problems can be divided into two types. The first type is that we can only consider the final results of fatigue process fracture. The failure probability is P f(N)=P(N fN) . The second type is that we must consider the fatigue process and take the component's strength (i.e. residual strength) as the function of cyclic number N . It's failure probability is P f(N)=P . We assume that the stage of the crack initiation is finished. Then the residual strength R a...