In view of the over-current problem of wind turbines caused by voltage dips, the existing over-current suppression techniques based on virtual resistors cannot take into account both the over-current suppression effect and the fundamental frequency control performance. At the same time, the existing techniques do not consider the high-frequency steady-state performance of the system, leading to the poor harmonic suppression performance during the fault ride-through. In order to give consideration to both the performance of fault ride-through and the harmonic suppression during fault ride-through, the mechanism of over-current and transient flux suppression is studied by analyzing the mathematical model of doubly fed induction generator (DFIG) in the case of voltage dips, and based on the virtual impedance technique, an improved control technique for DFIG under voltage dips is proposed. In the improved control technique, an additional control loop is added to the rotor current control loop of the machine-side converter to suppress the transient flux oscillation and improve the performance of the DFIG. Furthermore, the parameters of the proposed virtual impedance link are designed and analyzed to ensure that the proposed control method can take into account overcurrent suppression performance, highfrequency performance and fundamental frequency control performance. Finally, simulation results verify the effectiveness and feasibility of the proposed improved control strategy.