Laboratory scale experiments were conducted to compare the performance of two types of sequencing batch reactor(SBR) systems, anoxic-oxic-anoxic-oxic $((AO)_2)$ SBR and anoxic-oxic-anoxic $(A_2O)$ SBR on the biological nitrogen and phosphorus removal. Also, the profiles of DO and pH in reactors were used to monitor the biological nutrient removal in two SBRs. The break point in the pH and DO curves at the oxic period coincided with the end of nitrifying activity at about 1 h 30 min in oxic phase, and the change in pH appears to be related to nitrate concentration. The TOC removal efficiency in $A_2O$ SBR was higher than that in $(AO)_2$ SBR. The denitrification was completed at the influent period. The 2nd non-aeration and aeration periods were not necessary for the nitrogen and phosphorus removal because of the low influent TOC concentration in this study. The release and uptake of phosphorus in $AO_2$ SBR was much higher than that in $(AO)_2SBR.$ In order to uptake more phosphorus, the 1st aeration period in $A_2O$ SBR should be prolonged.