IEEE standards have defined the maximum permitted harmonic current injected to the grid by distributed resources. According to the analysis of the stator current total harmonic distortion（THD） influenced by grid harmonic voltage in doubly-fed induction generator（DFIG）， there is a drawback of grid-connected vector control for DFIG in high power converter. Due to the low control bandwidth， this control strategy cannot suppress the harmonica current of stator. So the power quality cannot fulfill the IEEE standards in the full range of operating process. An improved vector control strategy based on the closed loop control of stator harmonic current is presented. It adds a separated control loop for harmonic stator current to fulfill the requirement of the standard. A 30 kW DFIG platform is implemented. Experiment result shows the THD of stator current is reduced by using this improved vector control strategy.