Abstract: To improve the nitrate removal ability of the polythene (PE) carriers in the moving bed biofilm reactors (MBBR), the liquid-phase chemical method was used to modify the PE carriers and the ability of advanced nitrogen removal denitrification of the modified PE (MPE) carriers also studied extensively. The results showed that the static contact angle of the MPE surface was 75.5° which decreased by 26.6% compared with that of PE. The MPE surface structure roughness was higher than that of PE through the scanning electron microscopy (SEM) observation, and the oxygen element content of MPE was increased and the surface structure was changed compared with PE using the energy dispersive spectra and IR spectra analysis. The denitrification ability of MPE MBBR was improved obviously compared with PE MBBR. When the influent NO₃^--N and TN of MPE MBBR were (8.5±1.5) mg/L and (14.3±2.1) mg/L, the NO₃^--N and TN removal were (75.2±7.0)% and (56.5±10.7)%, respectively, which were increased 20.8% and 58.1% compared with the PE MBBR accordingly.