The present invention provides a control protection system for a flexible direct current power transmission system. The system comprises: an A/D sampling cabinet, a main control cabinet, an on-off input cabinet and an on-off output cabinet. The main control cabinet receives data sent by the A/D sampling cabinet and the on-off input cabinet and a control instruction of an upper machine server; andthe main control cabinet sends generated control protection signals to the on-off output cabinet and the converter valve valve-based controller of the flexible direct current power transmission systemand reports data to the upper machine server. According to the technical scheme, data high-speed exchange between each board card through of point-to-point and point-to-multiphase communication linkmodes and through adoption of a high-speed Lvds backboard communication bus, and therefore reliability of communication is improved, and timeliness of a control protection function is ensured.