Since a couple of years ago, the topic smart grid has been discussed worldwidely by power companies, research institutes as well as communication companies.Smart grid was first proposed to accommodate renewable energy generation by utilizing the latest information and communication technologies.Then, the concept"smart"was expanded from smart measurement system, demand-side response, distribution automation to transmission grid intelligence.Smart grid becomes the trend of power grid development.By applying information technologies in the conventional power grid, smart grid improves the utilization rate of energy and power asset management.The energy saving effects of smart grid can help in emission control and global warming.A mature smart grid has two-way real-time high-speed communication channels in all sections of the power grid, and it integrates advanced technologies, such as, control, IT and management.The system is a self-healing sytem.Moreover, the power generation, distribution and utilization in smart grid can be optimized scientifically and systematically.In this paper, what is smart grid, the development and the current research of smart grid will be presented.The objectives, key technologies and potential obstacles for constructing a smart grid are discussed.Some issues relating to smart grid on power transmission and distribution as well as consumer side are also discussed.