Anaerobic sequence batch reactor and aerobic sequence batch reactor were combined to treat the piggery wastewater. The ASBR was used to digest the wastewater for primary organic matter removal. Infections of digestion time to the wastewater's BOD/COD and to the nitrogen removal in behind SBR were studied. The result indicated that the wastewater with 36 hours' digestion retained high BOD/COD ratio of about 0.4. The nitrogen removal efficiency of this kind of wastewater in behind SBR was high with the effluent NH4+-N concentration less than 10 mg/L and a removal ratio higher than 99%. The total BOD5 removal ratio of A/O SBR was higher than 98% but the effluent COD(Cr) concentration couldn't meet the discharging standard before coagulating sedimentation.