Abstract: In view of problems of low measurement accuracy, poor real-time performance and high cost of traditional gas monitoring system of coal bunker in coal preparation plant, gas monitoring system of coal bunker in coal preparation plant based on fuzzy control was designed. The system introduces frequency conversion technology into ventilator control when gas concentration changes, frequency converter is used to adjust rotation speed of ventilator in coal bunker: when the gas concentration is large, rotation speed is controlled to increase and ventilateel quantity is increased to ensure gas concentration does not exceed the standard; otherwise rotation speed is decreased to reduce energy consumption, thereby real-time online monitoring of gas concentration in the coal bunker is realized. The practical application results show that the system can significantly reduce mean and fluctuation of gas concentration in coal bunker, and effectively ensure safety of coal bunker in coal preparation plant.