PWM converter applies LCL filter structure to obtain high filtering performance. The interaction of passive components will cause resonance phenomenon in a filter, these oscillations need to use the passive damping or active damping to suppress. Not only passive damping will lead to the increase of energy consumption, but also reduce the efficiency of filter. Using active damping and applying appropriate control strategies can ensure filter performance while have less energy consumption compared with passive damping. An active damping control strategy is presented to suppress the oscillation between two lines. The active damping control strategy suppresses resonance based on state feedback pole assignment method, and uses weighted admittance functions to analyze and select the appropriate active damping gain to suppress low harmonics of PWM converter. The experimental results of capacity of 10 kVA PWM prototype converter are also given, the experimental results verify the effectiveness of the active damping method and the correctness of the gain setting damping method.