Abstract: For permanent magnet coupling, the modeling and simulation is finished by using the software of Ansoft Maxwell. It is concluded that the air-gap is smaller and the torque is greater. The simulation shows that the rule of torque is similar to the mechanical properties of asynchronous motor along with the change of slip. Under the constant torque load, the feasibility of the speed control is analyzed by adjusting the air-gap size. Moreover, the overall design scheme of permanent magnet coupling’s speed control institutions are put forward. By comparing the commonly several kinds of speed control technology in coal mine production, it is revealed that the permanent magnet drive technology is more suitable for the downhole environment. Finally the issue that using permanent magnet coupling controls the speed on pump load can produce significant energy saving effect and economic benefits is discussed.