With the development of DG, using its islanding operation ability to restore power supply after fault can effectively improve the reliability of power supply distribution network. In this paper, the power balance, number of islands and the effect of tie switch are all considered, and the comprehensive restoration of active distribution network is researched. Through the DG equivalence of standby contact line, DG and contact switch and all considered in the decision-making process in recovery, so the overall scheme superiority is improved. In the process of load restoration using DG, the type and control characteristic of DG are fully considered, and based on master-slave control mode the DG islands is divided, finally the load of each island is selected by the maximum load power circle algorithm. An improved genetic algorithm is used to solve the islanding problem, combined with the network structure of active distribution network and the master-slave control mode, two major constraints are put forward, and the concept of genomic and gene block is proposed. The crossover and mutation operation of GA are both based on genome, which effectively avoids the invalid solution. Finally, a simulation study is performed on a distribution network consists of 3 line, 7 sets of DG, and the results verify the effectiveness of the proposed method.