Research conclusions:(1)Both single freedom impedance model and multi—freedom vehicle—track coupling model can effectively evaluate the vibration isolation performance of the mat within 0—200 Hz frequency band,but the former is simpler,clearer of the mechanical concept,and has stronger practicability.(2)The vibration isolation performance of the mat is frequency selective,that it only has a significant role in isolation in a frequency band,and other bands had little effect and even increase vibration.The most significant isolation effect is at the natural frequency of the system before laying ballast mat where the acceleration insertion loss is about 16.3dB.(3)The worst isolation effect which enlarges vibration most apparent frequency is at the first order resonance frequency of the system after laying ballast mat, it should be attached to more attention when design ballast mat SO as to avoid coincidence with the natural frequency of structures which had vibration isolation requirements.(4)Single freedom impedance model presented in this paper can provide the valuable reference to the vibration isolation design of railway ballest bed.