A fan motor control device includes a zero-crossing detection unit, a phase control unit, an operation processing unit, a first rectifier element and a second rectifier element. The zero-crossing unit generates a synchronization reference signal to the phase control unit, which in turn generates a phase control signal to the operation processing unit. According to the received phase control unit, the operation processing unit generates a motor-starting processing signal to the first and the second rectifier element for driving a fan motor to rotate. Since the phase control unit provides the effect of controlling the fan motor's output power and rotational speed, it enables the fan to have increased rotational speed and provide improved heat dissipation and ventilation effects.