The research shows that the proper acceleration（RMS）of collecting dust from plate under impaction is about 50g. At present electrostatic precipitator’s impaction machine is basically designed by gradual experiences, experiments and revises. With heavy workload, this way is more complex and cost much because of the large structure of ESP. This paper studies the response of Electrostatic Precipitator’s Plate under impaction with finite element method, using dynamic analysis to accomplish the design of impaction device by the analysis of the acceleration distributing on impact, and provides evidences to upgrade ESP.