Abstract:At 11~15℃, in SBR the stability of shortcut nitrification was researched under low ammonia nitrogen (55±5mg/L). Results show that system could achieve good stability and removing effect under two kinds of the DO level (initial DO 0.9~1.5, 4.5~5.0mg/L).In 150cycles the nitrosation rate had been maintained above 95%, ammonia oxidation rate was more than 85%, and the average SVI was 35.22mL/g. At two DO average levels ammonia nitrogen removal Sludge load was 0.15, 0.23kgN/(kgMLSS·d) respectively. When the initial DO was 4.5~5.0mg/L, at 21~23℃ stable operation of the shortcut nitrification cannot be realized.Nitrosation rate fell to 70% after 42cycle.Butthe shortcut nitrificationcan be restored at 31~33℃. In this analysis and FISH test research, the activity of the NOB can be inhibited at 11~15℃ and 31~33℃ so that shortcut nitrification has a stable operation.