Based on the analysis of the unbalanced grid voltage theory and common presentation of voltage unbalance ,the out-put power of DoublySFedSmotor is deduced ,and the operating characteristics of DFIG is studied during unbalanced grid voltage .For the further research on the operating characteristics of DFIG ,the connection model of the DFIG and grid is built in Matlab / Simulink .Results have shown that ,with the increasing degree of the unbalance ,the out-put pulsation amplitude of active and reactive of the DFIG and stator-side and rotor-side , increase almost linearly .In the same unbalance, active pulsation amplitude is higher than the reactive power pulsation amplitude.