Based on the traditional vector control strategy oriented by grid-voltage，apart from the positive sequence and negative sequence currents，the nonzero sequence third harmonic current component whose phase difference is120°can be detected at the stator side of doubly-fed induction generator（DFIG）under unbalanced grid voltage conditions.Asymmetric current components would aggravate the motor windings overheating and affect the power quality supplied by DFIG.To suppress the negative sequence and nonzero sequence third-order harmonic current components on the stator，their causes are analyzed in detail under unbalanced grid conditions first.Then a mathematical model for DFIG under negative sequence and third harmonic synchronized rotation axis is built，and a modified negative sequence and third harmonic current control is presented.Finally，simulation and experiment results are found in agreement with theoretical analysis，showing that the improved control method is feasible in suppressing negative sequence and nonzero sequence third harmonic current components at the stator side.