Abstract: The design and implementation of a triplex-redundancy control system for direct-drive-valve (DDV) were presented. The total structure of the system was built up. The schemes of triplex-redundancy brushless DC motor, transducer and cross channel data link (CCDL) were analyzed. Meanwhile, the strategies of servo control based on variable-structure PID and redundancy management based on CCDL were researched. Experiment results suggest that the proposed system possesses well steady and dynamic performance, and maintains good operation characteristics after first or second electrical failure. Main characteristics of the system are that the range of angle is from -10° to 10°, the precision is less than 4′, and the bandwidth is up to 20Hz for dual redundancy and 15Hz for single redundancy. The system satisfies the DDV actuator of airplane.