Given the complexity and particularity of the hierarchical connection system of the Shanwu Project, its reactive power control strategy has been optimized and perfected. On the basis of the original reactive power control, overvoltage fast switching, fast switching after emergency shutdown, and backup reactive power control function are added. The overvoltage fast cut is designed such that when the AC side voltage rises sharply because of a fault, the AC filter can be quickly removed to ensure that the AC bus voltage runs at a safe level. Quick resection means that after an emergency shutdown of the project, the reactive power control function quickly switches off the filter banks to ensure the stability of the AC grid voltage. Back-up reactive power control means that when the two sets of DC station control systems are unavailable, the polar control interface panel PCI can effect the removal of the AC filter according to the AC bus overvoltage, thereby ensuring that the AC bus voltage is stable and maintaining the stable operation of the DC system. A simulation experiment verifies the correctness of the new strategy. Finally, the paper offers suggestions for improvement of backup reactive power control. This work is supported by the Science and Technology Project of State Grid Corporation of China (No. SGTYHT/ 18-JS-206).