Abstract: By using the theories of random vibration and the finite element method of dynamical analysis,the stochastic earthquake responses of the permafrost ground of Qinghai-Tibet Railway were analyzed,the stochastic earthquake characteristics of the ground were calculated,and the effects of the thickness of frozen soil on the stochastic characteristics of the earthquake motion were studied.As a result of an example,the natural frequencies and the maximum earthquake responses of this ground for various conditions were obtained.The results showed that the natural frequencies of ground would increase but its earthquake responses would decrease with the increase of the thickness of frozen soil.