A power system includes a base, two magnetic bearings mounted on the base, a shaft rotatably mounted on the two magnetic bearings, a flywheel mounted on the shaft, a motor connected with the flywheel, an uninterrupted power supply electrically connected with the motor, a utility power electrically connected with the uninterrupted power supply, a coupling connected with the shaft, a speed change device connected with the coupling, a generating device connected with the speed change device, a load electrically connected with the generating device, a recharge rectifier electrically connected with the uninterrupted power supply, and a reactor electrically connected with the recharge rectifier and the generating device. Thus, the enlarged torque of the flywheel provides the inertia power to enhance the generating power of the generating device.