This　study　aimed　to　investigate　the　short-term　response　of　abundant-rare　genera　and　antibiotic　resistance　genes　(ARGs)　to　azithromycin　(AZM,　0.05-40　mg/L)　and　copper　(1　mg/L)　combined　pollution　in　activated　sludge　nitrification　system　at　low　temperature.　Nitrification　was　as　expected　inhibited　in　stress-and　post-effects　periods　under　AZM　concentration　higher　than　5　mg/L.　Abundant　and　rare　taxa　presented　dissimilar　responses　based　on　full-scale　classification.　Conditionally　rare　or　abundant　taxa　(CRAT)　were　keystone　taxa.　Relative　abundance　of　ammonia-oxidizing　archaea　increased,　and　three　aerobic　denitrifying　bacteria　(Brevundimonas,　Comamonas　and　Trichococcus)　were　enriched　(from　9.83%　to　68.91%　in　total).　Ammonia　nitrogen　assimilating　into　Org-N　and　denitrification　may　be　nitrogen　pathways　based　on　predict　analysis.　29　ARGs　were　found　with　more　co-occurrence　patterns　and　high　concentration　of　AZM　(greater　than　5　mg/L)　caused　their　proliferation.　Impor-tantly,　expect　for　some　abundant　taxa,　rare　taxa,　potential　pathogens　and　nitrogen-removal　functional　genera　were　the　main　potential　hosts　of　ARGs.