Abstract: In order to establish a generalized optimal control framework, an optimal voltage control scheme for distributed microgrids based on primal dual gradient algorithm is proposed. An optimization problem was designed that followed the technical constraints of distributed generator output voltage and reactive power capacity, so as to achieve the optimal balance between voltage regulation and reactive power sharing. The problem was converted into a convex optimization problem for easy calculation. Furthermore, a primal dual gradient algorithm was introduced to solve the problems such as inseparability of objective function, unavailability of global average voltage, and constraints on global coupling reactive power. The effectiveness of the proposed method was verified by testing microgrid and bus distributed test system simulation.