Aiming at the value of Rayleigh damping parameters in dynamic system of vehicle-track-bridge, one dynamic model was taken as an example, consisting of a high-speed railway bridge with a span of 40m, a slab track and a high-speed vehicle model. The dynamic responses of the bridge and vehicle were calculated by BDAP V2.0 (bridge dynamic analysis program) and the effects of damping ratio and reference frequency were analyzed. Based on the band-pass filtering characteristic of Rayleigh damping model, a unified method to obtain the value of Rayleigh damping parameters was proposed. The results indicate that the dynamic responses decrease with the damping ratio increased, including displacement and acceleration of the bridge, derailment coefficient and wheel unloading rate. The acceleration of the vehicle only changes a litter. When the damping ratio and ωi keep constant, the dynamic responses increase with the ωj increased, as the damping ratio decreased. Some suggestions about the value of Rayleigh damping parameters are presented, that is, the damping ratio is suggested as a smaller value from a certain closed interval according to the material types, ωi the fundamental frequency of the structure (ω1), ωj the highest excitation frequency under track geometry irregularity (ωf) through dividing the highest speed by the smallest wavelength of track geometry irregularity.