Abstract: A control method and apparatus for a compression system, and an air energy heat pump water heater. The compression system includes a compressor, a first electronic expansion valve, and a second electronic expansion valve. The method includes executing a first control step at least once, including determining a first target step number of the first electronic expansion valve; after the first electronic expansion valve is controlled to operate for a first time period according to the first target step number, determining a temperature difference between the current exhaust temperature of the compressor and the current highest water temperature of the water tank; when the temperature difference is less than a first preset value, decreasing the first target step number by a first correction step number; and controlling the first electronic expansion valve to operate according to the decreased first target step number.