An analytical method is proposed to calculate the interaction between operation stresses and shot peening caused residual stresses. The obtained variation of residual stress is integrated into Findley model to predict the fatigue life of shot-peened materials. Biaxial stress state is taken into account in conventional Findley model, and critical plane is studied for both in-plane and out-of-plane shear stress. In the end, taking example for AISI 4340 steel, the prediction of fatigue life is made for two different shot peening conditions. A good agreement between measurements and predictions can be observed.