Abstract: Abstact:Author analysis the methods to get soil thermal parameters in typical loess area and carries out field test.The test data shown that the initial average temperature by reactive power cycle is closer to the actual situation than the moving temperature inside the tube.When the local buried pipe depth is 120 m,the heat transfer performance of DN32 double U tube is improved by 20%-35%compared with DN25 double U tube,while the heat exchanger depth is 150 m,the heat transfer performance is only improved by about 3%.When buried at a depth of 150 m,the heat transfer performance of DN32 double U tube decreased by 19%—26%compared with that at a depth of 120 m.At 150 m depth,the heat transfer performance of DN25 double U tube decreased by 2%—6%compared with that of 120m depth.The analysis shown that when the tube diameter is the same,the heat transfer value of the buried tube decreases with the increase of the buried tube depth.