Dynamic Wireless Power Transfer (WPT) technology, with broad prospects, provides a safe and convenient charging solution for electric vehicles and promotes the development of electric vehicle industry. In this paper, the WPT system is modeled by Generalized State Space Averaging (GSSA) method and the influence of system parameters on the dynamic characteristics of the system is analyzed. Based on this model, a controller design method which can intuitively adjust the stability and response speed of the system is proposed and verified by simulation.