This paper presents a detailed review of the existing methods of the optimal control of distributed generation system and the state of the art of current research. The research of the optimal control of distributed generation system is summarized in terms optimal dispatch and control strategy. The approach of modeling and analysis for distributed generation system is described in detail. The key difficulties of the theory and technique about the optimal control of distributed generation system are analyzed. The current issues about the optimal control of the system are pointed out at last, and the research orientations of the optimal control of distributed generation system are presented.