Aiming to give some advices on the ground coupled heat pump system design in Sichuan Province,China,a typical ground source heat pump(GSHP)system in Sichuan Province was tested in a whole operational year,and the parameters of temperature and flow rate in different parts of system were measured during this period.The seasonal energy efficiency ratio was calculated and the performance of heat pump system in summer was compared with that in winter.The result shows that the coefficient of performance of the system reaches 3.63 in summer and 3.49 in winter,respectively.The heat balance in underground rock mass is acquired basically throughout the year,and the heat accumulation in the earth tends to be zero.