Abstract: The classification，principles and characteristics of the solar-assisted heat pump system are summarized，and some latest researches on collector evaporator and system capacity matching as well as some related properties of the direct-expansion solar-assisted heat pump system(DX-SAHP) are stated．Based upon these results，the main technical problems of the DX-SAHP are analyzed，and a series of thoughts and methods of improving the collection efficiency and optimizing system matching to improve the efficiency of this system are proposed．