Abstract: Microgrid is an autonomous system that integrates power generation, power distribution and power consumption, which builds a new energy technology fair competition system that has long-term technical, economical, environmental and social significance. Initially, the AC, DC and AC/DC microgrids are explained from power supply mode point of view,and the energy storage technology of microgrid is introduced. Then detail characteristics, special architecture, optimization algorithm and development law of each level control for hierarchical control are analyzed emphatically, the problems and research directions of each control are pointed out, the planning and design method of microgrid are discussed, and the security protection mechanism of microgrid is studied. In the end, the relationship between microgrid and energy internet is expounded according to current status, and the future development suggestion of microgrid is presented.