A parallel connection general aircraft pneumoelectric hybrid power system, including an internal combustion engine, a continuously variable transmission device, a centrifugal clutcher, a storage battery, a motor, a decelerator, an LNG storage tank and an LNG carburetor; a power output shaft of the internal combustion engine is connected with the continuously variable transmission device, an inner disc of the clutcher is fixedly provided on the output shaft of the continuously variable transmission device in a sleeving mode, an outer disc of the clutcher is fixedly provided with an outer gear ring in a sleeved mode, an input shaft of the decelerator is fixedly provided with a first gear in a sleeved mode, the first gear meshes with the outer gear ring; the storage battery is connected with a power supply port of the motor, a main shaft of the motor is covered in a sleeving mode with a second gear, the second gear meshes with the outer gear ring; the second gear relative to the main shaft of the motor only has linear freedom of movement, a fuel inlet of the internal combustion engine is connected with a fuel outlet of the LNG storage tank through the LNG carburetor; a fuel supply assembly is arranged between the internal combustion engine and the LNG carburetor, the LNG storage tank is assembled with a storage tank self pressurization assembly. The hybrid power system adopts the internal combustion engine using liquified natural gas as fuel, the method lowers the pollution to environment, and guarantees the endurance capacity of aircraft.