Construction of smart grid pilot projects was started by SGCC in May, 2009. As a key basic node of robust smart grid, smart substation is important for smart grid construction. Assessment of smart grid pilot projects was started by SGCC in March, 2011. Assessment index system for pilot projects of smart substations is built, combined with development of smart substation technology of China, based on principles of comprehensiveness, objectivity, practicability and typicalness. The system contains indexes of technology, economy, sociability and practicability. Under this system, systematic assessment of intelligent level, engineering construction, operating effect, etc. for smart substations put into operation is done. The results objectively reflect intelligent level of smart substations and problems of design, construction and operation for smart substations. The research and application of assessment index system for pilot projects of smart substations provide basis and references for comprehensive promotion of smart substations in China during 12th Five-Year Plan.