The invention relates to a method for promoting the smoke dust migrating velocity of an electric precipitator, which pertains to the technical fields of gas discharge physic and environment engineering, etc. The method arranges a discharge electrode at the mid plate clearance between two adjacent collecting electrode plates, and the discharge electrode is close to the outlet end of the clearance;the migrating direction of smoke dust is the same as the flowing direction of fume; the side clearance interval of the two collecting electrode plates at the direction of facing the gas flow is about30 percent of the width of collecting electrodes; the fume flowing speed passing the side faces of the two collecting electrode plates is 5m/s to 25m/s; the voltage of direct current applied to the discharge electrode is 20-56kV. The method promotes the ion transport rate and the ion concentration of the discharge clearance as well as increasing the charged coagulation rate of the smoke dust, thereby promoting the smoke dust migrating velocity of the electric precipitator and solving the problems of poor performance, large volume, large roller steel consumption and high operation cost, etc. caused by the low migrating velocity of the smoke dust in the electric precipitator.