Belt conveyor is one of the key transportation equipment in coal mining operation. The DTL120/200/3×630 belt conveyor of Huayang No. 1 Coal Mine is analyzed. Aiming at the problems of low automation and energy waste in constant speed operation, the whole scheme of automatic control system is designed. Using various types of sensors to monitor the running state of the belt conveyor, the monitoring results are fed back to the frequency converter, and the motor speed is controlled to match the coal conveying amount with the belt speed and save energy. After the control system is put into use, the field test shows that the application effect is good and the expected effect is achieved.