To reduce energy consumption of buildings on heating and cooling, and to achieve long-term stable heating and cooling using solar-ground coupled heat pump system (SGCHPS) in severe cold zone, a method of depending on seasonal solar heat storage in soil was put forward to maintain soil heat balance and increase system efficiency. Long-term experiment of 3 years was carried out relying on a demonstration project of solar-ground coupled heat pump for heating and cooling in severe cold zone. The system configurations were determined according to the building load, and 4 modes were selected to operate alternately. The experimental results showed that SGCHPS with seasonal heat storage could make the room achieve indoor air design temperature, and the guaranteed rate of heating and cooling were 92.0％ and 84.1％, respectively. The energy efficiency ratio (R_EE) of heat pump was more than 4, the annual heating EER including the power consumption of heat storage was about 6, and the cooling EER was more than 20. The system operated stably for a long period, and could meet the heating and cooling demands of a detached house in severe cold zone (e.g. Harbin). Seasonal heat storage took full advantage of solar energy of the whole year, and increased system efficiency. The energy-saving effect was remarkable.