With increasingly stringent environmental requirements, particularly in the emission concentration of dust, the older power plants used electrostatic precipitators could not increase the electric field due to space limitations, so they has been unable to reach the new emissions requirements, now the transformation of electrostatic precipitator must be imperative. The three kinds of transformation programs of electrostatic precipitator were described: increasing electric field, transforming ESP into electrostatic precipitator and bag filter, transforming ESP into bag filter. Rehabilitation programs through comparison of above methods and 4# boiler bag filter of Xibaipo Power Generation Company Limited by the electrostatic precipitator to the transformation of the bag filter,the bag filter was an efficient, stable,and could not be influnced by rust specific resistance,had higher capacity of particulate removal than the electrostatic precipitator,so the transformation technology was mature ,would be gradually promoted.