Abstract: The air compressor includes: a housing assembly, wherein the housing assembly has a first installation cavity, a second installation cavity and a rotation-shaft cooperating cavity, and the first installation cavity has a gas inlet and a gas outlet; a rotor shaft, wherein the rotor shaft is rotatably fitted inside the rotation-shaft cooperating cavity, and extends into the first installation cavity and the second installation cavity; a pressure wheel, wherein the pressure wheel is nested to the rotor shaft and is located inside the first installation cavity, and the housing assembly is provided with a controlling flow channel for communicating the gas-intake side and the wheel-back side of the pressure wheel; and a driving assembly, wherein the driving assembly is nested to the rotor shaft and is located inside the second installation cavity.