Asphalt mixtures was prepared with different polyester fiber contents(0%, 030%, 035%, 040%, 045%, 050%) and different coal gangue powder replacement rates(0%, 25%, 50%, 75%, 100%). The semicircular bending fracture(SCB) test was carried out to study the decay law of coal gangue powder/polyester fiber asphalt mixture under the erosion of different concentrations of NaCl solution. The results show that the flexural strength of the asphalt mixture gradually decreases with the increase of the concentration of the NaCl solution. Adding an appropriate amount of polyester fiber and coal gangue powder can significantly improve the flexural performance of the asphalt mixture. When polyester fiber is 04% and coal gangue powder replacement rate is 50%, the anti erosion ability of asphalt mixture is the best; The ultimate tensile stress of asphalt mixture has a good correlation with ultrasonic wave speed; The erosion damage factor B can be used to evaluate asphalt mixture. The corrosion resistance of the asphalt mixture, and with the increase of B, the damage degree of the asphalt mixture also increases.