To address voltage violation issues caused by the high proportion of distributed generation in distribution networks, this paper proposes a coordinated voltage control strategy that integrates modular dynamic zoning and the snow ablation optimization (SAO) algorithm. First, the dynamic zoning criteria for active distribution networks are clarified, and a sensitivity-based electrical distance zoning method is introduced. On this basis, a dynamic zoning evaluation system is established by comprehensively considering modularity, sensitivity, and cluster-level voltage self-regulation capability. Second, an objective function for voltage optimization control in active distribution networks is constructed, and the SAO algorithm is employed to efficiently solve the model. Finally, a modified IEEE 33-bus distribution system is used for simulation analysis. Through quantitative comparisons with traditional clustering-based zoning methods and the classical particle swarm optimization algorithm, the effectiveness, superiority, and adaptability of the proposed method are verified. The results demonstrate that the proposed method achieves more balanced power allocation among clusters, effectively improves node voltage stability, and reduces distribution network power losses.