Abstract: Current-carrying capacity of submarine cables directly determines transmission efficiency and operational safety of offshore energy projects. To investigate the impact of environmental parameters on current-carrying capacity of submarine cables under different laying conditions, a 220 kV cross-linked polyethylene insulated submarine cable was taken as the research object. COMSOL software was adopted for numerical simulation to systematically explore influence rules of key parameters, including seabed thermal resistivity, seawater temperature, laying spacing, and burial depth in seabed laying mode, as well as the material of horizontal directional drilling pipe, filling thermal resistivity inside the pipe, and laying spacing in horizontal directional drilling laying mode. Results showed that seabed thermal thermal resistivity, seawater temperature, and burial depth exhibited a significant negative correlation with current-carrying capacity, while laying spacing showed a positive correlation. Effect of burial depth decreased sharply when depth exceeded 7 m; severe thermal interference occurred when laying spacing was below 5 m, thermal coupling nearly vanished when laying spacing was above 15 m, and multi-circuit arrangement aggravated adverse coupling effect of burial depth and laying spacing. For horizontal directional drilling sections, current-carrying capacity was dominated by casing material, filling thermal resistivity and laying spacing, and high-thermal-conductivity metallic casings filled with low-thermal-resistivity medium such as water could effectively improve cable ampacity. The research conclusions of the paper could provide a scientific basis for optimizing laying parameters of submarine cables and achieving accurate calculation of their current-carrying capacity.