Economically　and　efficiently　removing　nitrogen　from　oxytetracycline　pharmaceutical　wastewater　(OPW)　is　a　challenging　problem.　To　address　this,　this　study　established　an　anaerobic-oxic-anoxic　sequencing　batch　reactor,　integrating　a　process　involving　partial　nitrification　(PN)　and　post-denitrification　(PDE)　to　treat　OPW　(PNPDE).　When　the　average　total　nitrogen　in　the　influent　was　110　mg/L,　the　effluent　nitrogen　level,　nitrite　accumulation　ratio,　and　nitrogen　removal　efficiency　were　12.7　mg/L,　95.1　%,　and　88.7　%,　respectively.　Extracellular　polymeric　substances　(EPS)　played　a　crucial　role　in　PNPDE　stability　and　oxytetracycline　degradation;　EPS　increased　from　34.1　to　66.3　mg/gVSS　during　operation.　In　a　typical　cycle,　exogenous　denitrification,　simultaneous　nitrification-denitrification,　and　endogenous　denitrification　were　the　main　nitrogen　removal　pathways,　contributing　19.8　%,　21.3　%,　and　48.7　%,　respectively,　of　nitrogen　removal.　Meanwhile,　41.2　%　of　oxytetracycline　was　degraded,　generating　eight　low-toxic　biotransformation　products.　High-throughput　sequencing　results　indicated　that　functional　microorganisms,　such　as　Nitrosomonas,　Ellin6067,　OLB8,　Candidatus_Competibacter,　Persicitalea,　and　Thauera,　played　a　crucial　role　in　removing　nitrogen　and　degrading　OTC.　PNPDE　provides　a　novel　solution　for　effective　and　energy-saving　OPW　treatment.　©　2024　Elsevier　Ltd