A highly stable and reliable blade server cooling system based on MPC8245 + FPGA fan controlled system is introduced, and threshold-based fan speed control strategy is used. In the proposed control strategy only when the temperature reaches a preset threshold would the fan speed convert between temperature rise curve and the temperature drop curve, non-stationary noises caused by the frequently fan speed modification to which the temperature fluctuation led, have been greatly reduced. The reliable, precise fan speed control method is implanted using improved reset circuit and PWM control circuit. The result of various tests and trials show that the blade server fan control system can control the fan speed precisely.