Flexible DC transmission technology is widely used in domestic and international applications, and the scale and capacity of flexible DC transmission systems are gradually increasing. For the flexible DC transmission control system, the functions of each level of the control system are discussed, and the complex hardware architecture and functions of the converter valve control system are elaborated in detail.Aiming at the safe and stable operation of the valve control system, the safety design scheme of valve control equipment in functional architecture, redundant backup, fault monitoring and other aspects is discussed. Considering the complex hardware configuration of the valve control system, he internal communication problem of valve control equipment is mainly studied. In addition to the basic communication links between the multi-level and multi-CPU of the valve control equipment, a dedicated communication verification monitoring channel is added to monitor the correctness of the communication content in real time; the key communication fault within the valve control is associated with the fault of the valve control equipment, so as to avoid more serious faults caused by communication fault, which provides a guarantee for the safe and reliable operation of the flexible dc converter valve.