Abstract: Based on the heat transfer theory, in the state of nature refrozen, the plane differential equation and initial boundary conditions of the temperature field of a pile foundation in a frozen soil region are presented considering hydrology-geology conditions and the initial ground temperature field and phase transformation effect. Taking the test pile engineering as an example, the numerical model of plane is established. The numerical results are in good agreement with the test results. The process of the refrozen both of the pile and frozen soil were analyzed. The conclusion is as follows: the distribution of temperature of the pile is asymmetry after casting, the change of temperature is nonlinear, and the core region of heat disturbance is ascertained.