To solve the overvoltage problem caused by reverse power flow in a distribution network with high penetration of a Distributed Generator (DG), this paper proposes a double-layer partition voltage regulation strategy based on an improved Fast-Newman algorithm. The improved Fast-Newman algorithm introduces an improved modularity increment index that takes into account the location of the DG and reactive/active-voltage sensitivity matrices, partitioning the distribution network more meticulously and reasonably. The double-layer partitioned voltage regulation strategy first uses the improved Fast-Newman algorithm to partition the distribution network for Reactive Power Compensation (RPC) and Active Power Reduction (APC). Then the nodes in the partitioning results are selected to form a priority regulation node set. Finally, in order to cope with the nonlinear complex solution space caused by the complex power flow of the distribution network with high penetration DGs, the PSO algorithm is used to calculate the optimal RPC and APC dispatch values of each node in the priority regulation node set. It can optimize the power flow in the DG injection point to achieve a reasonable combination of reactive/active power regulation. We conducted case studies on IEEE33 nodes and improved IEEE123 nodes. It is shown that this strategy can not only regulate voltage of the entire network by dispatching fewer nodes’ RPC and APC, but also bring a more stable voltage than a non-partitioned strategy. This work is supported by the National Natural Science Foundation of China (No. 61876040).