This paper intr o duces the wo rking pr inciple of electr o st atic pr ecipitato rs, and discusses t he r elat ion betw een co llectio n efficiency and plat e cur r ent , plate vo ltage and pow er of cor ona in. It shows t hat the effectiv e co ro na pow er is t he key facto r to impro ve dust co llectio n efficiency . Energ y-sa ving measur es a re sug g est ed based o n t he abo ve r esults.