The invention relates to a redundancy control method for a flexible direct current transmission system, and belongs to the field of an electric power system. The method adopts two control systems which are a main control system and a redundancy control system, wherein the two control systems are identical in function and can control operations of the whole direct current transmission system independently at specific conditions. The main control system carries out control on a flexible direct current system and transmits operation control information to a redundant system through a high-speed optical fiber at the same time, and the redundant system stays at a hot standby state. When the main control system is abnormal, the redundant system identifies automatically and completes control for the flexible direct current system automatically according to the received operation control information before the abnormity, the redundant system turns into the main control system, and the original main control system is notified to turn into the redundant system. According to the method provided by the invention, the redundant system automatically completes control for the flexible direct current system when the main control system is abnormal, the failure rate of the system is reduced, and the operation reliability of the system is improved.