The invention discloses a gas-jet engine and belongs to the technical field of gas engine equipment. The engine comprises a gas compression rotor, a gas jet rotor, a base, a starting motor, a fuel injection pipe and an igniting device; the gas compression rotor is positioned in a left chamber of the base; the gas jet rotor is positioned in a right chamber of the base; the rotation axes of the gascompression rotor and the gas jet rotor are overlapped and the gas compression rotor and the gas jet rotor rotate synchronously; the gas compression rotor is used for sucking air from the axial direction to make the air be mixed with fuel or gas from the outlet of the fuel injection pipe; a plunger on the gas compression rotor is used for compressing the mixture into a main combustion chamber of the gas jet rotor to realize combustion so as to generate high-temperature and high-pressure gas; the high-temperature and high-pressure gas is increased and pressurized by a jet flow valve arranged onthe gas jet rotor and is then injected out of a tangential nozzle arranged on the gas jet rotor, therefore the aerodynamic force generated can push a rotor to rotate and output power. The gas-jet engine disclosed by the invention has the characteristics of being compact in axial structure, high in work reliability, wide in speed regulation range, large in output torque and the like.