Abstract: The converters at rotor and grid side of DFIG have such ability as reactive power regulation, and can play their reactive power auxiliary function according to operation requirements of its accessing to wind farms. In this paper, wind farm which is regarded as a continuous reactive power source is involved in the control of reactive power and voltage under the premise of optimized active power output of DFIG, and immune genetic algorithm (IGA) is used as solution method under the uncertainty condition of reactive power output for doubly fed induction generator. On this basis, the influence of different capacity of wind generators and the location of wind farms integrated power grid on reactive power optimization are discussed according to the demands of wind farms construction. The objective function is built with the minimum sum of system loss of power system and voltage deviation, and its feasibility is verified through analyzing on the improved IEEE 30 node system.