When the oil gun for boiler is operating, in order to avoid that the pulverization of oil gun is poor,  the unburnt oil drop pollutes the pole plate of electrostatic precipitator and the deducting efficiency of the electrostatic precipitator is reduced, therefore the electrostatic precipitator can not be put into operation, however the electric heater and electric rapper shall be put into operation firstly in order to avoid the dew formation in the surface of the insulator and cause flashover short-circuit, and to timely enable to make the dust on the pole plate rapped and to prevent the reduction of deducting efficiency.