Abstract: Current carrying capacity is an important parameter of submarine cable operation scheduling, and the accuracy of its calculation is of great significance to submarine cable line engineering. At present, the commonly used calculation method of cable current-carrying capacity at home and abroad is IEC series standards. Introduction In order to make up for the defects and deficiencies of IEC algorithm in calculating the current-carrying capacity of long-distance AC submarine cables, it more accurately reflects the effect of submarine cable capacitance current effect and the influence of submarine cable metal sheath grounding method on cable current-carrying capacity, and provides theoretical guidance for practical projects. In this paper, 500kV single-core AC submarine cable is taken as the research object. Method Based on equivalent thermal path analysis, ATP-EMTP software is innovatively used to correct and calculate the metal sheath loss factor λ1 and armor loss factor λ2 in IEC loss calculation. The modified metal sheath loss factor and armor loss factor are brought back into IEC formula to calculate the long-distance submarine cable carrying capacity more accurately. Results Through the principle analysis and comparative verification, the results show that the submarine cable capacitance current effect and the submarine cable metal sheath grounding method have a great influence on the cable current-carrying capacity, which reflects the accuracy and advantages of the submarine cable current-carrying capacity correction method in long-distance AC submarine cable current-carrying capacity calculation. Conclusion For long-distance AC submarine cable lines, the modified current-carrying capacity can better reflect the actual current-carrying capacity of the cable.