The common numerical solution method of the moisture and heat coupling for the soft rock in cold region tunnels is introduced. The temperature field and moisture field in the surrounding rock of Dabanshan tunnel at its exit kl06+025 in the cold region is numerically simulated by software Femlab; the law of moisture-heat coupling transfer in the soft rock tunnel is analyzed. The frozen circle will be thinner when taking into account the moisture field and be much thinner if the seepage coefficient be increased. The moisture field influences the redistributing of temperature field greatly. The simulating result shows that the frozen depth of vault is the deepest; the below of vault’s is deeper and the side wall rock’s is the thinnest and the result is similar to the engineering experience. The software Femlab is proved to be applied to provide some reference for the engineering design if the necessary data is collected through the simulating example.