With the increasing scale of distributed generations connected to active distribution network, voltage/var control of distribution network is facing more and more technical challenges. In this paper, under the background of photovoltaic high-permeability distribution network, a three-stage voltage/Var control (VVC) is adopted to optimize the active power loss and voltage level of the distribution network from multiple time scales. First, coordinate and optimize the operation of capacitor bank and on-load tap switch in the first stage. Then, the second stage realizes the reactive power scheduling optimization of photovoltaic inverter. Finally, the response of the inverter's reactive droop curve to the voltage offset is considered in the third stage. Given the uncertainty of PV output and load demand, a stochastic optimization method is used to solve the three-stage VVC model. The feasibility and effectiveness of the strategy are verified by numerical simulation.