Abstract: Analyses the framework and principle of the power train based on a permanent magnet DC motor with an augmentor magnet, that has been used on an electric touring bus successfully. Considering various states of IGBT1, transient mathematical models of the electric motor driving system during the acceleration process is built up. Using Matlab/Stateflow, the controller model is also built up according to the control logic. Based on this, the transient mathematical model of the bus is set up, with the positions of the acceleration pedal signal as the (input.) The acceleration process is simulated and validated and dynamic characteristics of the power train in acceleration is analyzed. Transient simulation of the acceleration process clarifies the dynamic process of the power train, and is thus helpful in understanding the control of power train.