The invention relates to the technical field of substation automation of power systems, and particularly relates to a plug-and-play high-voltage equipment online state detection system. According to the plug-and-play high-voltage equipment online state detection system, through arranging a collection device to store self-description information of sensors, various output signals of the sensors with different interfaces and different data types can be processed, so that massages having a uniform data structure are formed and are uploaded to a monitoring device; the monitoring device receives and stores the self-description information of the sensors; and according to the self-description information of the sensors, the sensors, the collection device and the monitoring device are matched oneanother to implement plug and play of the sensors.