Abstract: Abstract: The heating tower heat pump system used air as its cold and heat source, whose performance will drop as the ambient temperature decreases during heating periods in winter conditions. Thus, a household solar assisted closed type heating tower heat pump system which could be used for the rural buildings in southern Shaanxi area was developed, which mainly include a solar heat collector, a hot water tank, a closed-type heating tower, a heat pump unit and the pipes and values. The heating performance of the system under winter heating conditions was experimentally studied, and the complementary mechanism of solar thermal energy and air thermal energy was preliminary analyzed. The results show that, first, under single heating tower heat pump model, the heating capacity of the system is in 12.3 to 15.0 kW, the COP of the heat pump unit is in 2.3 to 3.5, the SEER of the system is in 1.5 to 2.1, under the solar assisted heating tower heat pump model, the heating capacity of the system is in 12.1 to 15.2 kW, the COP of the heat pump unit is in 2.7 to 3.3, the SEER of the system is in 1.8 to 2.4, the heating temperature is higher than 41 °C under two models, which could meet the temperature demands of building heating in southern Shaanxi area. Second, the temperature of cooling water has a greater impact on the power consumption of the compressor than that of antifreeze solution, for every 1 °C increase in the average temperature of cooling water, the power consumption of compressor increases by 98.1W, and for every 1 °C increase in average temperature of the antifreeze solution, the power consumption of the compressor decreases by 9.5W. Third, under the single heating tower heat pump model, the change in the heat absorption of the heating tower is consistent with the change of ambient temperature; under the solar assisted heating tower heat pump mode, the absorbed solar thermal energy by the antifreeze solution is consistent with the change in the temperature of hot water tank, and the change of the heat absorption from ambient is opposite to the change of the ambient temperature, but the total heat absorption of the antifreeze solution still maintains a consistent trend with the ambient temperature; else, when the fan frequency is fixed, the heat pump unit changes the heat absorption from ambient and solar water tank of the antifreeze solution by changing the heat exchange temperature difference between the antifreeze solution and solar water and the air, to achieve complementarity with the solar thermal energy and air thermal energy. It is recommended that in actual applications, the heating temperature should be avoided too high to reduce the power consumption of the compressor, and when the temperature of the hot water tank is high, the frequency of the fan should be reduced to decrease the power consumption of the fan to improve the system SEER, but the hidden dangers may bring to the safe operation of the system.