The invention discloses an efficient large-temperature-rise single-stage-throttling intercooling heat pump water heater. An outlet of a high-pressure compressor communicates with a cooling agent inlet of a first condenser. One path of a cooling agent outlet of the first condenser communicates with a cooling fluid inlet of a subcooler through a first throttling device, and the other path of the cooling agent outlet of the first condenser communicates with a subcooled liquid inlet of the subcooler. A gas outlet of the subcooler communicates with an inlet of the high-pressure compressor. A liquid outlet of the subcooler communicates with an inlet of a low-pressure compressor through a third throttling device, a check valve, a second throttling device and an evaporator. An outlet of the low-pressure compressor is divided into two streams; one stream of the outlet communicates with a cooling agent inlet of a second condenser through a first stop valve, and a cooling agent outlet of the second condenser communicates with an inlet of the second throttling device; the other stream of the outlet communicates with a gas inlet of the subcooler through a second stop valve. A main cold water inlet communicates with the second condenser and the first condenser through a water pump. A hot water outlet of the first condenser serves as a main hot water outlet. According to the efficient large-temperature-rise single-stage-throttling intercooling heat pump water heater, the energy consumption is effectively reduced, the energy efficiency is improved and the working range is enlarged.