As the important part of smart grid, smart substation is the acquisition source of operating data and command execution unit, and also acts as the important foundation and support of strong smart grid. Along with the change of power grid development, the innovation and development of management model and the progress of science and technology, new requirements have been put forward for the development of smart substation. The top-level design of new generation smart substation is studied to propose its construction goal and function characteristics, as well as its overall framework and technical route. Finally, the core technology of smart substation and the development direction and technical scheme of key equipments are discussed.