Abstract: Nitrogen oxides (NOx) contribute a lot to photochemical smog, acid rain, ozone depletion and urban grey haze weather. In this paper, nitrification/denitrification mechanism and the progress of membrane biofilm reactor (MBfR) on NOx removal were introduced. A polysulfone hollow-membrane biofilm reactor (MBfR) for gaseous NO removal was investigated in air medium condition. Bacterial community composition and function of nitrification/denitrification were analyzed. The kinetic model between mass transfer and NO biodegradation of MBfR were elicited. The N-TiO2/PSF hybrid catalytic membrane biofilm reactor based on nitrification/denitrification was operated for the treatment of simulated flue gas under nature light or UV irradiation, inlet O2 concentration on NO removal was evaluated. This provides a new way of flue gas denitration using a membrane biofilm reactor (MBfR) and scientific basis for potential application value.