This thesis is concerned with the speed control of a brushless DC (BLDC) fan motor by switching its coil currents. Because fans are the most common cooling devices for computers, the demand for a quit and efficient fan that is capable of automatically regulating its speed according to temperature grows with each passing day. A mixed linear and switching control scheme which consists of two loop of feedback compensation for a two-phase BLDC fan motor is presented. Roughly speaking, the linear outer loop is mainly for speed regulation, and the inner loop is to generate a switching control signal while doing plant compensation. This control structure is simple and effective, emphasizing on low power consumption, accurate velocity regulation and low switching noise. The performance and stability requirement can be easily met by tuning several positive coefficients in the controller. The experiment shows an average steady-state regulation error of 0.563% in the range of fan¡¦s speed from 1050 to 2231 r.p.m.