This paper proposes an optimization model for restructuring distribution network in consideration of grid-connected security constraints of DGs. First, the problems of improving regional load balance and ensuring emergency reserve of the upper-level power supply not exceeded after distributed generation connection are analyzed, and the distributed generations’ return current and the upper-level power reserve capacity are collectively called distributed generation grid-connected safety constraints. And then, two evaluation indexes of regional power total substation capacity and 10 kV feeders’ network structure are proposed. Subsequently, this paper proposes an optimization model for restructuring 10 kV distribution network in considering grid-connected security constraints of DGs. Immune genetic algorithm is used to solve the model that regional power total substation capacity is qualified but 10 kV feeders’ network structure is not. Finally, the effectiveness of the proposed method is verified by simulation analysis of a practical 10 kV distribution network’s restructuring and optimization problem. This work is supported by National Natural Science Foundation of China (No. 51577018).