Abstract: Due to the poor heat dissipation conditions of submarine cable in the J-tube, the accurate assessment of the hot spot temperature of the submarine cable in the J-tube is the basis for determining whether it becomes the bottleneck. The existing calculation methods mostly set the submarine cable load based on the maximum output of the wind farm, without considering the correspondence among wind speed, submarine cable load, and heat dissipation capacity of submarine cable, which may lead to temperature assessment deviations. Therefore, this paper constructed a three-segment analytical model of the platform section, air section, and seawater section, and established a calculation method for the conductor temperature of the submarine cable in the J-tube including axial heat transfer. Combining the influence of wind speed on heat loss and the convective heat transfer coefficient of air, the temperature assessment algorithm that couples wind speed, load, and heat dissipation was formed.Therefore, the method proposed in this paper can more accurately reflect the thermal characteristics of the J-shaped section of submarine cables and provide a reference for the capacity assessment and operation optimization of submarine cables.