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 monitor for wireless power transfer system combined with upper computer and lower computer was proposed. The LCC-S magnetic coupling WPT system was used as the monitoring object to analyze the monitoring system requirements. The calculation formulas of the WPT system energy efficiency parameters were given. The hardware and software design method of the lower computer based on STM32 and the upper computer system based on PC and LabVIEW was presented. The experiment results show the proposed design scheme and design method are suited for the energy efficiency online monitor of the wireless energy transmission system.