Abstract: The control rod drive mechanism reactor head cable and digital rod position indication system head cable developed and validated for third generation nuclear power plant was introduced.The structural design, material selection technology breakthrough were introduced, according to technical specification of the design institute and the application situation of the project.The cable insulation adopted the double-layer structure design and the new material application, meeting 60 years life requirement at the operating temperature of 150 ℃.The insulation material is PEEK, which can guarantee electrical performance and irradiation performance, and enhance the high temperature resistance of the cable.Using special high temperature extruder and strictly controlling the process parameters during production, PEEK achieves good crystallinity.