The invention relates to the field of energy saving equipments. The purpose of the invention is to provide a directly-heated heat pump water heater unit with high heating performance. The technical scheme adopted by the invention is that the directly-heated heat pump water heater unit comprises a compressor, wherein the outlet of the compressor is connected with the outer pipe of a double-double-tube heat exchanger, the tail end of the outer pipe of the double-tube heat exchanger is connected with an electronic expansion valve, the electronic expansion valve is connected with an evaporator, the evaporator is connected with a gas-liquid separator, and the gas-liquid separator is connected with the inlet of the compressor. The outer pipe of the double-tube heat exchanger is uniformly divided into multiple sections along the flow direction of a heat medium, the outlet of the compressor is connected with the sections of the outer pipe respectively through a diverter valve, and a one-way valve is arranged between every two adjacent sections of the outer pipe, and the inner pipe of the double-tube heat exchanger is connected with each of a tap water pipeline network and a water storage tank. The directly-heated heat pump water heater unit disclosed by the invention can enhance the heat transfer rate of a heat transfer medium and water, and greatly improve the heating performance of the directly-heated heat pump water heater unit.