Bridge surface roughness is usually considered to be the main Influencing factors of vehicle-bridge coupled vibrations.The way that obtaine Bridge surface roughness by the transformation of power spectral density is effective and rapid.The Bridge surface roughness is obtained by Fourier inverse transform method and trigonometric series method respectively. It can be concluded from the comparision that the precision of Fourier inverse transform method is higher than trigonometric series method. The vibration functions for 4-dofs Vehicle and bridge were derived with the employment of d'Alembert principle and computational procedures for vehicle-bridge coupled vibration were compiled. The dynamic response of a simply supported beam and vehicle was analyzed considering bridge surface roughness which was obtained by Fourier inverse transform method.The research shows that the influence due to the bridge surface roughness is significiant and vehicle speed also effects the bridge vibrations by changing the frequency of the force acting on the bridge due to vehicle and the force acting on the vehicle due to bridge deformation.