Abstract: Aiming at the problems of complex laying environment of submarine cables and the influence of multiple factors on the calculation accuracy of current-carrying capacity, this paper takes the three-core AC submarine cable as the research object, and constructs an electromagnetic field-temperature field coupling simulation model based on COMSOL by the finite element method to realize the accurate simulation analysis of the temperature field and current-carrying capacity of submarine cables. Firstly, the structural characteristics and operating thermal characteristics of submarine cables are sorted out, and the key influencing factors such as laying depth and soil thermal conductivity are determined. Secondly, the equivalent thermal circuit model and COMSOL simulation model are built for comparative verification, and the influence laws of each parameter on the cable temperature field distribution and current-carrying capacity are analyzed through single-factor simulation experiments, with corresponding optimized laying suggestions put forward. This simulation method can reflect the thermal characteristics of submarine cables in actual operation for subsequent research, and provide data support and technical reference for the engineering design, laying optimization and current-carrying capacity verification of submarine cables.