Smart grid construction is a long-term and complicated systems engineering that is not only related to technical issues， but also the participation of society as a whole. The concept causes， development needs and essential cause of the smart grid are analyzed， and its deep implication is revealed. In particular， in the early stages of smart grid development， it just won't do to merely emphasize the outward performance of“smart” to the neglect of the physical carrier and the development of supporting technology. The reliability principles must be followed and the basic structure of power grid reinforced to globally achieve the efficient optimal coordination between security and economy. Finally， related technical requirements and key breakthrough points of smart grid construction are elaborated in order to provide a useful exploration of China's strong and smart power grid construction at the essential cause level.