Abstract: According to the essential theories of heat transfer and seepage,considering the coupled effects of seepage field and temperature field,three-dimensional computational model of the coupled problem was given,the finite element formulae of this problem were obtained by Galerkin’s method,and the computer program of the finite element was written.Using this model and the program,three-dimensional nonlinear analysis for the coupled problem of seepage field and temperature field of the flat excavated part from DK977+578～DK977+682 in Kunlun Mountain tunnel on Qinghai-Tibet Railway were made.It was shown that the effect of seepage field on temperature field in the tunnels in cold regions was very large,and seepage field should be taken into account during the design.