Distribution network lines heavy overloads, voltage instability and other problems occur easily due to large-scale distributed photovoltaic access. The existing economy-centered distribution network photovoltaic hosting capacity optimization assessment method is difficult to meet the distribution network voltage stability need. This paper proposes a quantification method for photovoltaic hosting capacity of distributed network based on static voltage stability margin. First, the analytical equation of static voltage stability index characterized by photovoltaic output power is derived, which reveals the quadratic function relationship between distributed photovoltaic output power and static voltage stability index. Then, with the maximum capacity of distributed photovoltaic access as the optimization objective, a quantitative model for distributed photovoltaic hosting capacity of distribution network is established by considering the constraints of static voltage stability margin, distribution network line loss rate, voltage magnitude, and reactive power compensation device, and an improved adaptive genetic algorithm is used to solve the nonlinear model. Finally, case studies on an IEEE 33-node system validate effectiveness of proposed method in guiding distributed photovoltaic construction in distribution network.