Polyphenylene sulfide (PPS) has good corrosion resistance, chemical stability, and thermal stability, which was widely applied in precipitator field. In this paper, a novel in situ synthesis protocol was selected to fabricate the Mn–CeO
x
/PPS functional composites with excellent low-temperature denitration activity. Results show that the as-obtained Mn–CeO
x
/PPS filter possessed of superb denitration activity at 180 °C under a weight hourly space velocity of 210,000 mL/gcat/h, which may be stemmed from the generation of amorphous and well-dispersed mixed metal oxide catalysts.