Abstract: Based on the annular vacuum of vacuum tube collector can suppress the convective heat loss around the heat absorber,which can achieve higher collector temperature and collector efficiency compared with traditiona flat plate collector,this paper proposed an evacuated tube type direct-expansion solar-assisted heat pump,which combines evacuated tube collector with direct expansion solar heat pump. This paper experimentally investigates the effects of solar radiation intensity and circulating water temperature on system performance under typical operating conditions,and explores the dynamic performance of the system under the condition of compressor frequency conversion. The results show that increasing solar radiation intensity and decreasing circulating water temperature are beneficial to improve the system performance. The system achieves the maximum COP of 5.36 at the radiation intensity of 850 W/m2and circulating water temperature of 55 ℃. The COP of the system with the compressor frequency of 42 Hz is 4.08,which is 1.23%,8.5%and 13.6% higher than that of 45,47 and 50 Hz,respectively.