Abstract: After building up the testing equipments of the gas temperature of electrostatic fabric filter，the suitable detectors and controlling method were selected through the simulation of flue gas temperature． For keeping filter bag from damage by high temperature flue gas，the technology of bypass，spray cooling，cold air mixing and low temperature ( pressure ) economizer were developed． We also developed the system of monitoring the pressure of dust cleaning and pre-coating for filter bag． Test of interactive linkage between bypass valve and lift valve were also carried out，to prevent the flue gas path from saltation，realizing the safty protection of the system of the bag filter as well as the boiler．