Abstract: Aiming at the problems of complex laying environment of submarine cables and the calculation accuracy of current-carrying capacity affected by multiple factors, this paper takes three-core AC submarine cables as the research object, and establishes a COMSOL-based electromagnetic-temperature field coupling simulation model using the finite element method to realize accurate simulation and analysis of the temperature field and current-carrying capacity of submarine cables. The structural characteristics and operating thermal characteristics of submarine cables are analyzed to identify key influencing factors such as laying depth and soil thermal conductivity. An equivalent thermal circuit model and a COMSOL simulation model are built and verified by comparison. The influence laws of various parameters on the cable temperature field distribution and current-carrying capacity are studied through single-factor simulation experiments, and suggestions for laying optimization are provided. The proposed simulation method can provide a basis for the thermal characteristic analysis of submarine cables in actual operation, and offer data support and technical reference for the engineering design, laying optimization and current-carrying capacity verification of submarine cables.