A laboratory-scale A²O process treating domestic wastewater was carried out to investigate the influence of amoxicillin on nitrogen and phosphorus removal in pharmaceutical park wastewater treatment plant. The removal efficiency of COD, nitrogen and phosphorus had been studied before and after adding amoxicillin to influent. The result revealed that the activity of organism degrading bacteria was significantly inhibited and the average removal efficiency of COD decreased from 86.9％ to 79.5％ by the impact of amoxicillin (2-5 mg·L-1). The activity of nitrate bacteria was not inhibited while nitrite bacteria was significantly inhibited that the nitrification activity had been declining. The average removal efficiency of ammonia decreased from 95.5％ to 85％. The anaerobic phosphorus release, the denitrification performance and the removal efficiency of total phosphorus and total nitrogen was slightly affected.