Wireless power transfer (WPT) technology has been applied to many fields of production and life. When the WPT system is running and debugging, the system needs to be monitored to understand the actual working conditions of the system. In this paper, a design scheme of energy efficiency performance monitor for wireless power transfer system combined with upper computer and lower computer is proposed. The LCC-S magnetic coupling WPT system is used as the monitoring object, and the monitoring system requirements are analyzed. The calculation formulas of the WPT system energy efficiency performance parameters are given. The hardware and software design method of the lower computer based on STM32 and the upper computer system based on PC and LabVIEW is presented. The experiment results show the proposed design scheme and design method are suit for the energy efficiency performance online monitor of the wireless energy transmission system.