The experiment studies the phenomenon of simultaneous nitrification and denitrification (SND) in SBBR filled with polyurethane as micro-organisms immobilized carriers. Polyurethane fills in SBR as micro-organisms immobilized carriers, formation of a Sequencing Batch Biofilm Reactor (SBBR). Under the anaerobic/aerobic conditions, we studied the effects of C/P, C/N and DO on SND. The results showed that when COD was 400mg/L, C/P was 43.2~50.2, C/N was 9.41~11.9 of the influent, the concentration of DO was 3.31~4.01mg/L, the effect of TN removal was good. When C/P was 46.9, C/N was 10.3, the concentration of DO was 3.58mg/L, the removal rate of TN was 83.71%, TN effluent was 6.45mg/L. TN effluent followed byⅠA standard of “Discharge standard of pollutants for municipal wastewater treatment plant”. DO concentrations impact the forms of nitrogen in the effluent. C/P, C/N and DO play an important role on SND in SBBR filled with polyurethane. Controlling these factors effectively can inhance the effect of nitrogen removal.