A motor system with reduced common-mode noise includes an AC power, a first transformer unit electrically connected to the AC power and providing a first DC power, and a second transformer unit electrically connected to the AC power and providing a second DC power. The first DC power is supplied to a motor driving section of the motor system, and the second DC power is supplied to a motor controlling section of the motor system. Therefore, a common-mode noise from the transformer winding for the motor driving section can be prevented from coupling to the transformer winding for the motor controlling section. Moreover, a safe stop signal is applied to turn down a PWM IC for power through a photo coupler or a relay. Therefore, the first transformer unit stops supplying current to the motor driving section of the motor system to enhance safe stop function for the motor system.