The invention belongs to the technical field of engines, and relates to a one-key start type gasoline engine. The one-key start type gasoline engine comprises a gasoline engine body and a carburetor arranged on the gasoline engine body. A thermoswitch and an air pump are arranged on a shell of the gasoline engine body. An arc hole concentric with a main shaft is formed in the outer end of a rocker, controlling the aperture of a main air door and fixed to the main shaft, of the carburetor, a rotation shaft of the thermoswitch is connected with a drive arm, the drive end, driven by the drive arm, of the outer end of the push rod is inserted in the arc hole so that the thermoswitch can be used for controlling the aperture of the main air valve, and a pressure sensing cavity of the air pump communicates with an air inlet pipe of the gasoline engine; a control rod of the air pump and the outer end of the rocker are connected in a hinged manner so that the air pump can be used for controlling the aperture of the main air valve. During cold engine start or hot engine start, the air door can be automatically opened or closed according to the regulated time, manual intervention of apertureof the air door is not needed, the starting actions are simple, the starting success rate is high, and one-key starting of the engine can be achieved.