Abstract: After anaerobically digested, the biodegradability of piggery wastewater became poor. Its value of BOD₅/COD fell to 0.19, moreover carbon and nitrogen was inversive, which brought much difficulty for anaerobically digested effluent to aerobically treatment. If Sequencing Batch Reactor(SBR) was used directly to treat anaerobically digested effluent, the treatment efficiency was very poor, with only 8.31% for COD removal rate, and 78.7% for NH₃-N. A significant improvement in system performance was achieved by increasing the biodegradability of anaerobically digested effluent of piggery wastewater. The removal rate for COD, BOD₅ and SS reached 89.6%～93.4%, 97.9%, 95.6%, respectively, especially, the removal for NH₃-N was more than 99%, an extremely high rate. The result of study was applied in piggery wastewater treatment plant, the SBR system worked well. The removal rate for COD was about 90%, that for BOD₅ and NH₃-N was larger than 98% and 99% of respectively. A satisfactory effluent quality from SBR, with COD＜300 mg/L, BOD₅＜20 mg/L, and NH₃-N＜10 m/L, was achieved. The removal of TN also reached more than 90%.