Limited fossil fuels for heating and cooling building as well as air pollution make people to use and utilize renewable energy, i.e., solar energy and ground heat energy. Ground source heat pump is regarded as the future and attractive energy-saving system using for the whole society. In this paper, a ground source heat pump system with the power of 16.6 kW has been established firstly, and then the soil temperatures of four buried depths have been experimentally tested, finally the values of COP in this system have been calculated by the testing parameters. The results show that the soil temperature changes slightly from 11:00 to 18:00 in the testing six days. The results also show that the values of COP in this system range from 1.56 to 2.01, which is lower than other system. The present paper contributes to the knowledge of the soil temperature distribution characteristics and COP value for a real system in a spring season, when the system has a small building load. (C) 2017 Elsevier B.V. All rights reserved.