The removal performance of 11 veterinary antibiotics in piggery wastewater and their accumulation in the activated sludge were studied in an intermittent aeration membrane bioreactor (IAMBR) at different COD/TN ratios and organic loads. The results showed that both antibiotics and chemical oxygen demand (COD) were efficiently removed at hydraulic retention time (HRT) of no less than five days and COD/TN ratio of 2.1, the removal rate was (79.1 ± 0.7)% for total antibiotics and was (88.4 ± 1.4)% for COD. As HRT was shortened to three days, the removal rate of COD was little changed but the removal rate of total antibiotics was significantly decreased. As COD/TN decreased from 2.1 to 0.7, the removal rate of total antibiotics was little changed, but the COD removal rate was significantly decreased. Antibiotics of tetracycline and quinolone species kept accumulating in the sludge at long SRT, and the accumulation amount was decreased with shorter SRT. The concentration and composition of antibiotic in the sludge were influenced by the raw wastewater.