Based on erosion and fatigue experiment, the flexural strength, the relative dynamic elasticity modulus and the water absorption of the dry saturation surface were measured and the microstructures of concrete at different erosion days were investigated. Also, the coefficient K of combined effect was applied to characterize the superimposed effect of sulfate erosion and fatigue load. The results show that owing to the effect of fatigue load, there is no strength growth phase of the concrete in sulfate solution and the erosion fatigue factor is reduced with the increment of the time. The main reasons of erosion fatigue damage are the expansion products generated by sulfate erosion and the cracks produced by fatigue load. The mutually reinforcing effect of sulfate corrosion and fatigue load can be indicated by the K value calculation.