A converter substation is a special type of substations， whose functions and roles are more important than those of traditional AC substations， and its structure is also more complex. Hard cable interconnection between primary and secondary devices will be replaced by optical fiber network interconnection in digital smart converter substations， which enables information sharing in the process layer. The advantages of digital smart converter substations include improving accuracy of measurements and reliability of signal transmission， simplifying connections of secondary devices， solving interoperability problems between different secondary devices， enabling different applications to share one unified information platform to avoid duplication of devices， improving standards of automation operation and management， avoiding electromagnetic interference， surge voltage and two point grounding， reducing space occupation and time consumed for debugging problems and commissioning new substations. The ideas for construction of digital converter substations are proposed.