When class E inverter is used as an excitation source in magnetically coupled resonant wireless power transmission system (MCR-WPT), the equivalent load is directly related to the mutual inductance between the coils and the load of the system. It leads to the optimization design of the E class inverter more difficult. So the algorithm of mutual inductance between two helix coils and the trend of mutual inductance with the change of the distance between two coils was analyzed in this paper. This paper investigates transfer efficiency and output power of wireless power transmission (WPT) system. And the analytical relationship between equivalent load of class E inverter and transfer distance is also included. The designing method of parameters of MCR-WPT based on E class inverter with ZVS is given. Experiment result shows that when the distance between the coils is 26 cm, ZVS of the E class inverter is realized, and the system efficiency reaches 86.3%. The validity and accuracy of the theoretical and simulation analysis are verified by experiments.