Electro mechanical problem has been the focus of scientists for a long time. In order to explore how　to make motor rotation speed and direction of rotation control flexibly，an economical and simplified motor model based on a new rotating mechanism is proposed. Starting from mechanism of plate rotation and combining with simulation of COMSOL， the moment of force is analyzed theoretically，and the related influence factors of rotation are discussed quantitatively. The results show that the root cause of rotation is phase difference，and the moment of force coming from an attractive power leads to rotation. In addition， the rotating speed is proportional to the area sheet metal inserts and inversely proportional to the distance between sheet metal and plate. The direction of rotation depends on the position of sheet metal.