Abstract: Taking the shearer used in 14204 working face of Tongmei Zheneng Majialiang Coal Industry Company as an example, the power supplying design and controlling part design of the inverter system are analyzed, and some protection functions of the inverter system are expounded. In the automatic mode of coal mining, the haulage speed of shearer can be adjusted automatically according to the load of scraper conveyor. With the using of this shearer, the labor intensity of the staff is reduced, and the working efficiency is improved.