Abstract: It analyzes the research status of ring main unit partial discharge and expounds mechanical characteristics detection method of circuit breaker.It is necessary to implement the real-time monitoring for ring main unit partial discharge, mechanical characteristics of circuit breakers, temperature and humidity, water immersion and smoke.Based on this, an intelligent and comprehensive online monitoring system is built for the shielded solid-insulated ring main units.The partial discharge monitoring is based on Ultra High Frequency（UHF）and temperature, while mechanical characteristics of the circuit breaker monitoring is based on current analysis to build a test system.After on-site installation and commissioning, the equipment is running well with stable and accurate monitoring data, which provides a reference for establishing online monitoring systems for solid-insulated ring main units in the industry.