Abstract: The technology of “taking heat without taking water” in medium-deep geothermal heat pump system is the core and the main factor affecting the performance and design of the whole system.To get a more comprehensive understanding of the medium-deep geothermal heat pump system performance, in this paper, the testing of medium-depth geothermal heat pump system is of great significance to guide the design and operation of the system.The measurement for a medium-depth geothermal heat pump system with depth of 3 183 m in Shanxi Province are made, including the average initial soil temperature, heat exchange capacity and operation parameters.Some results and data are obtained and analyzed.The initial bottom hole temperature is 107 ℃.The average initial soil temperature is about 70 ℃.The heat exchange capacity per length of tube is 217.4 W/m.The coefficient of performance of the system is about 1.99 when partial load rate is about 25%, with 70 ℃ of supply water temperature and radiator terminal.The research can provide reference for system design and operation.