The EMI filter is one of the most effective methods to suppress the noise of the LED driver.In the traditional design,little attention was paid to the character optimization of the DM (differential-mode) EMI filter in the LED driver.The studies show that the near-field coupling in the EMI filter can affect the distributed parameters of the EMI filter.And a new method by series resonant which includes an X capacitor and an inductor to improve the performance of the DM EMI filter around the resonant frequency is proposed in this paper.The resonant inductor can be controlled by the nearfield coupling.The relative distance,the relative angles and the coupling polarity between the components can be adopted to control the nearfield coupling of the EMI filter.Besides,the EMI filter with additional magnetic path is proposed to control the near-field coupling.The experiment results verify the proposed method to be correct and feasible.