The possible reasons for the invalidation of polyphenylene sulfide (PPS) used in electrostatic-fabric integrated precipitator were explored by elemental analysis and infrared spectroscopy analysis. Based on the estimation for the acid solution concentration of the condensation of acid gases NOx and SO3 at low temperature, a diluted acid with an appropriate mass fraction (0%～5% nitric acid and 20%～35% sulfuric acid) simulating acid solution formed during the condensation process was used to test the anti-corrosion ability of PPS. The results indicate that the main reason for the degradation of PPS is the oxidation of PPS with the acid formed during the condensation. Compared to that of H2SO4 and HCl solution, the oxidation capacity of HNO3 solution is stronger, resulting in a significant decreasing to nearly 20% of breaking strength retention of PPS after the 168h-ageing. It could be reasonably inferred that reducing the dew point temperature of flue gas and the NOx concentration in the gas is of great importance in improving the service life of PPS.