Abstract: In order to improve the heat transfer efficiency of energy collector pipe, the authors calculate the different energy collectors from the angle of increasing heat transfer efficiency, and compare the calculations with the numeric simulation results. The comparison shows that reducing the pipe radius can improve the heat trasfer efficiency of energy collector. The authors also theoretically analyze the structure of energy collector, types and characteristics of secondary refrigerant and selection of backfilled stuff, and put forward the measures to enhance heat transfer efficiency in GSHP system.