Abstract: With the combination with the similar theory and analytic calculation, the single tube freezing problem under the surface temperature non-constant condit ion of the freezing tube was fully studied.The temperature filed distribution law with high accuracy, the radius of the freezing zone, the thermal flux density of the tube W all and the approximate calculation formula of the average temperature in the freezing zone were obtained and the relevant error would not be over 2%.The analysis sh owed that there would be four main factors influenced to the radius of the freezing zone, the thermal flux density of the tube wall and the average temperature of the fre ezing zone.Theoretically the paper explained the cause of less influence to the temperature field by the ratio of frozen soil volumetric specific heat to unfrozen soil Lc in the numerical caculation.In combination with the site measured data of the simulation test, the similar analytic solution of the freezing zone radius was verified.The max error between the similar analytic solution and site measured value was 5%.