To solve the reactive power optimization and voltage stability problem for wind farm, considering the static var compensator (SVC) in the smart substation connected with power system, a reactive power and voltage control strategy is proposed to coordinate SVC and doubly-fed induction generator (DFIG). The optimal trade-off solution of multi-objective reactive power optimization is obtained by learning automata. Voltage requirement of point of common coupling (PCC) for wind farm is satisfied. At the same time, the reactive power margin of reactive power source in wind farm becomes bigger. Finally, take a wind farm in East China as example for analysis, the simulation results show that the reactive power and voltage control strategy proposed is verified feasible and effective.