An experimental device is established in this paper, the operating condition of ground source heat pump under the condition of soil thermal imbalance in cold region in winter is simulated. The experiment studies the distribution characteristics of the frozen soil area around the buried pipe, and gets the average moving speed of freezing front. The results show that the distribution of frozen soil area is asymmetric. When the fluid inlet temperature is -15℃ and buried depth is 350,700 and 1 050 mm, the average moving speed of freezing front is 5,5 and 6.67 mm/h in the heat response areas of 40~60 mm, and the average moving speed of freezing front is 1.54, 1.82 and 1.82 mm/h in the heat response areas of 60~80 mm. The frozen soil to a certain extent in favor of heat transfer between buried pipe and surrounding soil, so the frozen soilshould be considered in the design of GSHP in cold area.