Unarmoured cables refer to cables without steel armor protection. The quality of the cable insulation performance is very important to ensure the safe operation of the power supply system, so how to detect the insulation performance of the cable and find the potential defects of the cable as early as possible is very necessary. Most of the current research focuses on armored cables, but few people study the insulation performance testing methods of unarmored cables. The insulation detection methods used mainly include partial discharge method, optical fiber temperature measurement method, leakage current method and so on.