Abstract: A direct expansion solar assisted heat pump (DX-SAHP) system for space heating with solar heat collector/evaporator and fin evaporator in parallel is constructed, the thermal cycle process of the system is analyzed, an experiment platform of the system is set up. The experimental results show that the DX-SAHP heating system can obtain high performance under different operating conditions. The highest COP can reached 6.88. Compressor frequency, solar irradiance and ambient temperature all affect the heating capacity and COP of the system. The COP of the system running with solar collector/evaporator is nearly 30% higher than that of the fin evaporator under constant frequency, and nearly 45% under conversion frequency. The system has better performance under conversion frequency operation mode.