Based on the control and protection scheme of H400 converter valve, the design and realization of interface between DC control & protection system and the control & protection of converter valve are illustrated in detail. The type and function of signals between converter control and protection (CCP) and valve vase electronics (VBE) are demonstrated, including optical control signals, electrical I/O signals and so on. The effectiveness and reliability of the control & protection interface technology of converter valve are proved by the application in the Ningdong-Shandong HVDC transmission project.