Abstract:The insulating materials of 500 kV AC self - contained oil - filled ( SCOF) submarine cables currently consist of two main types: kraft paper and PPL paper. Considering the huge differences between these two types including cost,insulation performance and dielectric loss performance,the first investment,annual operational cost,application experience and safety stability should be taken into consideration to make a final choice. Taking Hainan interconnection project for example,the performance and differences between these two insulating materials are introduced,and the technical and economical comparison is carried out based on different armour type,return conductor structure and reactive power compensation,etc. ,which may benefit other projects.