The access of distributed generation will have a certain impact on the distribution network vulnerability. Firstly, a new method for the identification of distribution network vulnerability lines based on grid operation status and topology is proposed. On the one hand, the voltage stability index is defined based on the power flow calculation results; on the other hand, the complex network theory is applied to the distribution network, and the weight index of the line load is used to define the importance index. On this basis, considering the access location and access capacity of distributed generation, this paper summarizes the influence of the vulnerability of distribution network affercted by distributed generation. Finally, the reasonable and effective of the method is proved by the simulation of the IEEE33 node distribution model.And providing a theoretical basis for the transformation of distribution network and the planning of distributed generation.