Affected by the access of power electronic equipment and the distributed capacitance of the submarine cable, the traditional differential protection is difficult to fully protect the offshore wind power AC submarine cable line. Therefore, a protection scheme of offshore wind power AC submarine cable based on relevant principles is proposed in this paper. Firstly, the correlation difference between line differential current and braking current is used to form a protection criterion. On this basis, the influence of distributed capacitive current of submarine cable line on correlation was analyzed. Then, by normalizing the current amplitude on both sides, the ability of the protection scheme to withstand capacitive current was improved. Finally, the effectiveness of the proposed protection is verified by simulation. The simulation results show that when the length of the submarine cable line is 150km with no compensation, the proposed protection scheme can still operate correctly within 5ms.