Abstract: By the research of square wave magnetizing current model of portable magnetic powder machine, it is found that the yoke coil will cause the peak current when the current of coil is reversing. In this paper, a magnetization current model based on trapezoidal wave is proposed. It makes the coil current of the magnetic yoke reverse smoothly and reduces the peak current to avoid the peak current damage to the drive circuit. The experimental results show that the optimization model can reduce the average current of the battery by 31.96% and improve the life time of the magnetic powder machine by 46.98%. It has certain reference significance.