Through flexural test at low temperature， the decay law of the low temperature performance of asphalt mixture under freeze thaw cycles with salt was analyzed by maximum flexural tensile strain， flexural stiffness modulus and strain energy density. The effects of fiber addition and the other modifiers on the low temperature performance of mixture were investigated. The results show that maximum flexural tensile strain and strain energy density of asphalt mixture decrease rapidly after freeze thaw cycles with salt， while flexural stiffness modulus increases. With increasing the number of freeze thaw cycles， the variation degree decreases gradually. The higher the mass fraction of salt in the solution and the lower the change of freeze thaw temperature， the larger the influence on strain energy density of asphalt mixture. The variation show exponential function between strain energy density of the mixture and the numbers of the freeze thaw cycles with salt. The improvement of basalt fiber on the low temperature performance of asphalt mixture is very significant under the condition of freeze thaw cycles with salt.