This study designs an indoor power transmission line thermal aging monitoring system in combination with the visible light sensors, infrared sensors and electromagnetic induction device. The electromagnetic induction device is used to detect the position of the power transmission cable in the wall. The infrared sensor uses a multi-point temperature measurement method to monitor the temperature of the wire in the wall or the wire in the distribution box. The visible light sensor is used for video monitoring and taking pictures of abnormal parts. If problems such as abnormal data are found, the device transmits abnormal data and photos to the host computer through the Ethernet communication module. Users can view the temperature of the current monitoring point, real-time video monitoring of the current monitoring point and set the temperature and electromagnetic force threshold through the mobile APP client or PC client. Once the monitored temperature and electromagnetic force data exceed the thresholds, the system will issue a line aging warning, the user can receive the mobile phone APP and PC client alarm push and picture information of abnormal parts, timely process the aging cables, avoid electrical fires caused by aging lines.