Abstract: This paper adopts a new type of power electronics - soft normally open point (SNOP) to solve the bottleneck of bus/branch in distribution network, and improve the DG penetration capacity in flexible distribution network (FDN). Firstly this paper establishes the optimization model of the allowable capacity of DG in the FDN. A new multi-population genetic algorithm (MPGA) is used to get the global optimal solution in three cases, including fixed position of DG in traditional distribution network, fixed position of DG in FDN and free integration of DG in FDN. Then this paper builds the system model of IEEE 33-bus distribution network to verify the conclusion, which finally proves that the application of SNOP in FDN will allow more DG accessing the network. What is more, this method has a great reference value to determine the optimal capacity and access location of DG in the future FDN.