The semi circle bending （SCB） test of coupling effect of salt-freezing cycle （the concentration of NaCl is 0%， 7.0%， 13.0%， 26.5%， and the number of freeze-thaw cycles is 0， 2， 4， 6， 8） was carried out with 50% replacement rate of coal gangue powder and 0.4% polyester fiber content， the influence of salt freeze-thaw cycle on the internal damage and deterioration process of the specimen is studied. The results show that when the concentration of NaCl solution is 13.0% and the freeze-thaw cycles are 8 times， the salt-freezing coupling action has the strongest erosion and damage effect on asphalt mixture， and the internal damage of the specimen is the most serious； when the mass ratio of coal gangue powder to mineral powder is 1∶1 and the content of polyester fiber is 0.4%， asphalt mixture can have high viscosity， becoming dense and thick asphalt film and three-dimensional network structure formed by fiber， which can well alleviate and reduce the damage of salt freezing erosion to asphalt mixture. The ultimate tensile stress damage is fitted by Poly2D model， and the fitting coefficient is 0.944.