Smart distribution system is the basic part of smart grid. With the dramatic changes of electric power generation, transmission mode and utilization diversity, the development and operation of distribution systems face not only the pressure in technology application and equipment innovation, but also many new challenges related to integration of distributed generation, electricity market reform and integration of cutting-edge technologies in other areas. The characteristics of smart distribution systems are analyzed in terms of energy flow, information flow and power market, and key technologies are proposed which should be addressed in the near future, including planning of active distribution systems, self-healing control, situational awareness, asset management, information and communication technology (ICT) application, integration of distributed generation, energy storage, etc.The development roadmap of smart distribution systems is illustrated to provide a reference to power system researchers.