Considering the change of frozen soil phase, the finite element method of unsteady temperature field-seepage field coupled problem was improved. According to the soil freezing characteristic curve, the pore ice containing volume was calculated and fixed. At the same time, a correction method of temperature derivate unfrozen soil’s water volume, and a new method accelerating the convergence speed were put forward, to eliminate the numerical oscillation phenomena that appears in the frozen soil’s temperature field-seepage field coupling calculation, and accelerate the convergence speed. Finally，two numerical examples were compared with the experiments to verify the reliability and effectiveness of the method.
