Currently, ultrasound–based wireless electricity transmission (WET) is a very valuable research technology, but it has problems such as low electricity transfer efficiency and high safety hazards. In this manuscript, we propose the double matching layers structure–based ultrasound wireless electricity transmission system (DWET) with high efficiency and high safety, which can be used for internal condition monitoring of closed metal cavity equipment such as gas pipelines, submarines and gas storage tanks. According to the mason equivalent circuit model, the electricity–ultrasound–electricity conversion process of the system is converted into a circuit model of a two–port network, and the double matching layers structure of the ultrasonic transducer is introduced in this process for analysis. An experimental test system was built to test and analyze the input–output characteristics of the whole system, and the measured results have a high degree of fit with the simulation results. The final experimental results show that the electricity transfer efficiency of the system is improved from 29.3% to 36.5%, and the output capacity of the system is improved. And most importantly, the designed system has a high degree of safety, which accelerates the application of ultrasound wireless electricity transmission technology for wireless health monitoring of closed metal equipment.