Abstract: It was found that the composition of flue gas from coal-fired boiler affects adversely the mechanical properties of PPS(polyphenylene sulfide) filter during smoke dust removal. Simulating the flue gas conditions, the change in PPS filterability with the three factors, i.e., NO2 concentration, functioning time and temperature in NO2 atmosphere. The results showed that the mechanical strengths of the filter decrease obviously if the values of the three factors increases, and the retention rates of both the warp and weft filter strengths are just 55.8% and 48.7% at 3 mL/L, 120 h and 190°C. Some fibers of the filter are found broken from SEM images because of the oxidation of NO2, and the filter becomes darker in color with brittlement enhanced greatly after adding the oxygen atoms in the PPS molecule chain. NO2 is one of the reasons why the service life of the filter is shortened. So, the concentration of NO2 should be decreased on site via the technology measures available to take.