Abstract: In order to solve the voltage fluctuation problem in regional power network caused by the integration of distributed wind generation, a coordinated controlling optimization method for reactive power between regional grid and distributed wind power plant is proposed in this paper. A model for calculating the reactive power regulation capacity of wind farm is constructed firstly by considering the wind speed uncertainty and the wiring in wind farm. On this basis, by treating the uncertainty of wind output and load as the interval constraint, a bi-level reactive power optimization model of regional network is proposed, in which the upper-level is to minimize the power loss and the lower-level is to find the worst operation scenario of regional network, which reduce the losses while meeting the voltage operation requirements. In the end, the Genetic Algorithm and interior point method are used to solve the model, and by taking a regional power network as an example, the feasibility and effectiveness of the strategy are verified by MATLAB results.