Owing　to　the　complicated　environments,　the　service　life　of　bag-filter　or　electrostatic-bag　composite　precipitators　with　polyphenylene　sulfide　(PPS)　is　greatly　deviated　from　the　ideal　time.　In　this　paper,　the　structural　transformation　of　PPS-based　bag　filter　materials　collected　from　the　coal-fired　power　plants　with　different　loading　units　were　investigated　systematically.　As　the　SO2　content　increases,　the　surface　evolution　of　PPS　fibers　from　smoothness　to　crack　occurs.　An　opposite　trend　is　observed　for　melting　point　and　cross　breaking　strength.　The　major　reason　for　the　failure　of　PPS-based　bag　filters　is　that　working　temperature　(T)　often　passes　through　acid　dew　gas　point　(T-a),　and　the　SO3　would　be　produced　during　the　condensing　of　H2SO4　when　T　is　lower　than　T-a.　The　SO3　with　strong　oxidation　would　attack　the　weak　C-S　bonds　of　PPS,　resulting　in　the　oxidation　or　even　sulfonation　of　PPS-based　bag　filters.　This　work　discloses　the　actual　structural　evolution　of　PPS　and　some　corresponding　rules　under　the　complicated　corrosive　gases　with　high　temperatures,　which　provides　a　guidance　for　prolonging　the　service　life　of　PPS-based　bag　filters　during　the　usage　of　coal-fired　power　plants.