The failure of the aircraft spline shaft was attributed to overstressing, cyclic bending loads, and other complex conditions. This study investigates the bending fretting fatigue behaviours and failure mechanisms of 15–5PH stainless steel. The study analysed the residual stress, microstructure, morphology, and chemical state of the worn surface and the fatigue failure mechanisms. The results showed that fretting wear significantly reduces the bending fatigue life. The surface residual stress transitions from compressive to tensile stress states. The value of residual stress increased, and the oxygen content of the worn surface was higher in the mixed fretting regime. Fatigue fractures occur at a depth of 50–100 µm below the surface in the present experiment. Display omitted •The S-N curve for bending fretting fatigue of 15-5PH stainless steel is established.•The fretting wear contributes to the evident reduced bending fatigue life.•Bending fretting fatigue fracture sources are forms at 50-100 µm below the surface.•The surface residual stress changes from compressive to tensile stress states.