Abstract: 【Objective】 At present, the electronic current transformer, electronic voltage transformer and pure optical current transformer in DC converter station mostly rely on traditional technical means for operation and maintenance, and their operating status cannot be effectively monitored in real time. Operators can only observe the actual measured value of the measuring point , but cannot know whether the information related to the status of the measuring device itself is good or bad. The measurement device may be in an unhealthy operation state for a long time until it is damaged, which is easily found by the operator and cannot be eliminated in time, resulting in DC outage accidents. Therefore, it is urgent to adopt corresponding technical means to solve the problem that the measurement device cannot be real-time and effective monitored.【Method】 An online monitoring and intelligent early warning system for measuring device is proposed in this paper. By sorting out the monitoring data, the corresponding data acquisition and processing device, voltage transformer online monitoring device, data server and corresponding monitoring software are researched and developed, and a set of online monitoring software and hardware system for measuring devices in DC converter station is constructed. 【Result】 The practical application shows that it can collect, store, analyze and display the real-time operating data of measuring device , realize the graphical real-time status inspection of measuring system equipment of converter station, and provide the change trend of each state parameter. Based on the trend analysis of equipment operating status parameters, the online monitoring and diagnosis software system can evaluate the equipment status and warn the trend, and provide decision support for equipment maintenance. Based on the fault diagnosis technology, the key factors of equipment state mining and correlation analysis are realized, and the diagnosis conclusion and disposal method are automatically generated after the fault occurs, which can eliminate the equipment in advance and ensure the long-term healthy operation of the measuring device.【Conclusion】 The system can significantly improve the level of intelligent operation and maintenance of key equipment in DC converter station, and reduce DC power failure accidents.