In order to solve the problems of high energy consumption, low efficiency and high failure rate of limestone belt conveyor in raw material conveying system of raw material grinding section, the three-phase asynchronous drive motor of belt conveyor is transformed into permanent magnet motor drive system. After the transformation, the operation energy consumption of the drive system is reduced from 0.153kW·h/t to 0.107kW·h/t, and the annual electricity cost is saved by about 135 000CNY. The system with low noise, convenient maintenance, can be started with load, and will not affect other electrical equipment generate interference.