Together with the advantages of intelligent technologies, Smart Grid (SG) has become a topical research area in recent years. Considering the abundant and complex technologies it contains, the development of SG should be divided into several stages, and a well designed development strategy is required to improve the transition from current power grid to newly SG step by step. Facing outstanding challenges and problems, city power grid (city grid) resorts to intelligent technologies and management much more eagerly. A brief overview of current city grid is provided in this paper. A new concept of Smart City Grid (SCG) is proposed, and then, its advantages and the significant relationships between SG and SCG are described. According to the important role that SCG plays in SG, a bottom-up development strategy, aiming to simplify the development of future SG, is illustrated in detail, whose start is SCG. Depend on a standardized communication network, robust electrical connection, coordinated control and integrated management, the intelligent region could be expanded from a smart city grid to a nation-wide unified smart grid within this strategy.