Compared with the traditional microcomputer programming method, the control protection system with visual programming has the advantages of convenient operation and maintenance and high development efficiency. However, control protection systems for visual programming often require simultaneous multi-DSP programming. Traditional DC control protection systems are difficult to meet requirements of real-time, multi-line operation and compatibility. Aiming at these problems, the characteristics of visual programming of flexible DC control protection system are analyzed. A flexible DC control protection system suitable for visual programming is proposed. A software and hardware for visual programming of multi-line operation is designed. Finally, experimental verification was performed on RT-LAB simulation experimental platform. The results show that this system meets the requirements of DC transmission engineering application. Multi-line operation and independent bus communication can be realized. It has strong compatibility, high real-time performance and high engineering application value.