Abstract: To reduce the energy consumption of the heat pump system, the different solar heat pump drying systems were constructed. Based on the first law of thermodynamics, three thermal models of solar heat pump systems were constructed. The effects of solar radiation intensity, condensation temperature and evaporation temperature on COP（coefficient of performance）, evaporative heat load, heating capacity and compressor power consumption of single-stage compression heat pump, dual-stage compression heat pump and single-stage coupled compression heat pump were discussed. The results show that the heating performance coefficients of the three solar heat pump systems are all increased with the increasing of evaporation temperature and decreased with the increasing of condensation temperature. When the evaporation temperature, the condensation temperature and the heating capacity of three systems are all the same, the COP of the two-stage compression system is the largest, and the COP of the single and double-stage coupled compression system is the smallest. Under the condition of the same heat absorption, the single and double-stage coupled heat pump system has the largest heating capacity, while the two-stage heat pump system has the smallest heating capacity.