The invention relates to a power supply device in the field of electricity, in particular to a combined motor power supply device employing supercapacitors. The combined motor power supply device comprises a power supply module, a supercapacitor control module, a supercapacitor module, a regulation control module, a motor controller and a motor. The supercapacitor module includes two supercapacitor units connected in parallel. The motor is coaxially connected with a generator. An electromagnetic clutch is mounted between the generator and the motor. The combined motor power supply device has the advantages that the supercapacitor units cycle for charging and discharging, the generator operates constantly at the optimal speed with low economic power, the service life of the generator is prolonged, economic efficiency is improved, the supercapacitors are free of charging and discharging memory effect, abundant power and cruising power as high as possible are provided for EVs, charging efficiency of the EVs is improved, the generator and the motor operate coaxially, and charging efficiency is improved by adding the electromagnetic clutch between the generator and the motor.