The invention discloses a power generator of a range extender, relates to the technical field of power generators. The power generator of the range extender comprises a motor shell, a motor rotor shaft, a rotor assembly and a stator assembly, wherein the motor shell is of a semi-closed round disc structure and is provided with an accommodating space, the accommodating space is used for accommodating and fixing a part of the power generator, the motor rotor shaft is used for transferring power output of an engine in the range extender, the rotor assembly is arranged in the accommodating space and is used for converting mechanical energy to electric energy, the rotor assembly is of a round disc structure and is a common member of the engine and the power generator so as to reduce a dual-mass flywheel, and the stator assembly is used for moving relative to the rotor assembly, converting the mechanical energy to the electric energy and outputting the electric energy to a power supply. The rotor assembly is the common member of the engine and the power generator so as to reduce the dual-mass flywheel, and the quality of the power generator is reduced; and moreover, with the adoption of the round disc rotor assembly, the volume of the power generator is reduced, and the power generator is compact in structure and good in heat dissipation performance.