The built-in cable partial discharge online monitoring system is mainly used to monitor the partial discharge signals occurring in high-voltage cables and the connected high-voltage equipment. This system is an independent, distributed partial discharge detection system. It uses a flexible networking method for data transmission to conduct real-time online monitoring of partial discharges in the cable system. Through the built-in cable partial discharge analysis system, it evaluates the insulation status of the system, predicts the development trend of the partial discharge, prevents sudden electrical accidents, and provides effective data basis for the condition-based maintenance and overhaul of the equipment.