In order to finish the partial nitrification of wastewater with high concentration ammonia and low concentration carbon in SBR smoothly, the research had been practised in reactor that short-cut nitrification developed in depth. The relationship between concentration and nitration rate of ammonia nitrogen could be studied by degree of nitration, which controlled by alkaLinity. NO2-/NH4+ during partial nitrification need to reach 1.3 on condition that concentration of ammonia nitrogen and rate of nitrite accumulation was given. As it turned out, alkaLinity shortage tended to bring nitrosation of ammonia nitrogen to an end by extremely low pH values. There was a Linear relationship between initial alkaLinity dosage and ammonia nitrogen nitration level. AlkaLinity requirement that adapt to inflow of anaerobic reactor during partial nitrification could be ascertained by means of formula ΔN (1.3+X) =1.3N;y (initial alkaLinity) =7.744ΔN -205.2 (nitrite accumulation rate: X, ammonia nitrogen nitration demandΔN) .