Abstract: In order to investigate the train-induced ground vibration more accurately, a vehicle-track-ground coupling model is proposed. The source of vibration excitation is divided into two components: the axle load and the roughness-induced dynamic loads. The vehicle is simulated by a multi-rigid-body system and a Hertizian contact spring is introduced between each wheelset and the rail to consider the dynamic wheel-rail forces. Compatibility of the displacements at wheel-rail contact points yields equations for the dynamic wheel-rail loads. The Biot’s full dynamic poroelastic theory is employed for the saturated half-space, neglecting the body force and the compressibility of solid grain. The governing equations are solved by using the Fourier transform in the transformed domain. The results in time domain are obtained by applying the inverse fast Fourier transform (IFFT). The dynamic wheel-rail force is investigated for various exciting frequencies, and the dynamic response of the poroelastic half-space induced by both the axle load and dynamic load is presented. It is concluded that the dynamic load makes important contribution to train-induced environment vibration and can not be neglected in the engineering practice.