Abstract: The line commutated converter based high voltage DC（LCC-HVDC） transmission system has been widely used in largescale wind power transmission in China due to its large transmission capacity. When the commutation failure occurs in LCC-HVDC systems, the power grid voltage at the sending end will fluctuate dramatically due to the large range of reactive power fluctuation in the transient process, which has a huge influence on the stable operation of wind power and leads to the occurrence of off-grid accidents. Meanwhile, the commutation failure in DC systems is different from the short circuit fault in the AC power grid.Therefore, it is urgent to study the transient characteristics and fault ride-through method of the doubly-fed induction generator（DFIG）. Firstly, transient voltage characteristics of the commutation failure at the sending end are analyzed and the mechanism of transient overvoltage is revealed. Then, the stator flux characteristics of DFIG with the continuous change of the power grid voltage are analyzed by the piecewise linear description method. An improved active suppression strategy for low-and high-voltage ride-through and overvoltage is proposed for commutation failure according to the reactive power output equation of DFIG.Finally, PSCAD simulation verifies that the proposed strategy can not only achieve fault ride-through of DFIG, but also suppress the transient overvoltage, which improves the system stability and flexibility.