To solve the voltage instability and the reactive power margin issues caused by grid-connected large doubly-fed induction wind farm and static synchronous compensator, Comprehensively considered the voltage-deviation index and the margin optimization of the reactive power sources in large wind farm, hierarchical Coordination Control Strategy for Var- Voltage is proposed. The paper puts emphases on the reactive power distribution principles of doubly-fed induction generator units and static synchronous compensator.,and then its objective function is constructd, with particle swarm optimization algorithm solving multi-constrained nonlinear optimization Objective Function. Based on Matlab/simulink ,electric Power System simulation model of regional power grid with a wind farm was established and then simulation results verify the efficiency and effectiveness of the proposed control strategy.