Abstract: In order to improve the capacity utilization rate, safety and reliability of submarine cables, in view of the defect that the traditional conductor temperature and current carrying capacity calculation methods are only applicable to specific laying conditions, a two-dimensional finite element model of submarine cables and their laying environment is established using COMSOL finite element software by taking the three core 220 kV optical fiber composite submarine cables of a wind power project as the research object. The electromagnetic heat current multi physical field coupling is simulated and analyzed;the effects of seawater temperature, seawater velocity, burial depth and current carrying capacity on the temperature of submarine cable conductor are studied, and the empirical formulas of conductor temperature and current carrying capacity are derived by fitting the simulation results. The results show that under the default velocity and burial depth of the traditional model and IEC analytical formula commonly used in the engineering field, the relative error between the calculated carrying capacity of the simulation model and empirical formula and the traditional model and IEC analytical formula is within 7%; the error between the simulation model and the empirical formula is within 5%. The results show that the proposed simulation model and empirical formula can be used to analyze the variation law of download flow in different laying environments, and provide a calculation method for accurate estimation of current carrying capacity.