The design and implementation of speed control driver which is applied to three-phase brushless DC fan motor are presented in this thesis. In the back-EMF detection circuit, we use digital filter circuits to obtain commutation to overcome the switch noises which are generated by high frequency PWM, without using traditional capacitor filter circuits which need more volume for additional external capacitor. Because the problems of high frequency magnetizing vibration and dispensable power consumption are generated by open-loop fixed frequency PWM speed control approach, closed-loop speed feedback control methods and closed-loop current feedback control methods are adopted to achieve high efficiency and low vibration of the fan motor drivers.