In order to survey the vibration response of permafrost subgrade induced by train traffic along Qinghai-Tibet Railway,and provide the rational theoretical foundation for the rail transit assessment,the self-programming software of the train-track coupled dynamic system was employed to investigate the characteristics of the vertical applied force on sleeper induced by passenger trains.The researches show that,the simulation results of the self-compiling program are in accord with the field monitoring data,and the theory of the procedure is proper;the train-induced vertical acting force exerted on sleeper is in inverse proportion to the subgrade damping,and increases with the raising of the subgrade modulus and vehicle velocity,at the same time increases linearly with the rise of the rail gap;the dominant frequency bands are mainly within the action rate of shifting axle load,the vibratory energy reaches the maximum at the bogie action rate,and the sleeper vibration makes little different to the sleeper vertical applied force induced by passing trains;the effects of the freeze thawing status,rail gap width,and the train speed can not be ignored on the vertical acting force.Moreover,the function relationship of the acting force maximum value versus train velocity is given quantificationally.