Abstract: In order to realize rapid start-up of partial nitrification by using real domestic wastewater,the experiment of three same sequencing batch reactors(SBR) and the temperature is 25 ℃,the dissolved oxygen (DO) is 2.0 mg/L,the aerobic time is respectively TT/2、3T/4、7T/8(T was the time from the beginning of aerobic to the appearance of the "ammonia valley"),is conducted to investigate nitrite accumulation.The nitrite accumulation ratios(nar) were increased by 50%、47%、70% in the three reactors when the initiative pH value is 7.7-8.0,the nar increases fastest in which the aerobic time is 7/8T,the partial nitrification is achieved.The nar can be increased by appropriate aerobic time,by the effect of the pH value on the configuration of the nitrifying bacteria and by the inhibition of NOB to free ammonia.