An improved small-disturbance model of the doubly-fed wind generator is proposed in this paper. In comparison to traditional small-disturbance models, the proposed model comprehensively considers the mechanical rotation of the wind turbine, the shaft transmission in the gear box, the electromagnetic characteristics of the induction generator, as well as the control strategy for both rotor and stator, so that it is able to precisely describe the oscillation mode of the wind generator that is integrated into the power grid. In case studies, simulation results have verified the effectiveness of the proposed model, and different control strategies are applied to the doubly-fed wind generator to investigate their influences on its oscillation mode.