Sucralose　(SUC),　an　artificial　sweetener　widely　used　in　food,　beverages　and　pharmaceuticals,　is　frequently　detected　in　various　environmental　matrices.　Triclosan　(TCS)　is　commonly　used　as　a　disinfectant　and　often　co-exists　with　SUC　in　sewage　environments.　This　study　investigated　the　effects　of　SUC　(0.1–10　mg/L)　on　the　transmission　of　intracellular　and　extracellular　antibiotic　resistance　genes　(ARGs)　in　the　partial　nitrification　systems　with　and　without　TCS　pre-exposure.　The　reactors　operated　for　150　days,　and　SUC　did　not　affect　ammonia　oxidation　performance,　while　TCS　led　to　the　maintenance　of　partial　nitrification.　The　types　and　abundances　of　extracellular　ARGs　in　sludge　and　free　ARGs　in　water　increased　significantly　after　TCS　pre-exposure　when　faced　SUC　stress,　which　might　be　caused　by　a　decrease　in　α-Helix/(β-Sheet　+　Random　coil).　SUC　was　more　easily　to　enrich　ARGs　in　partial　nitrification　systems　with　TCS　pre-exposure,　exacerbating　the　risk　of　ARGs　transmission.　The　microbial　community　showed　stronger　relationships　to　cope　with　the　direct　stress　of　SUC,　and　the　functional　bacteria　(Thauera　and　Nitrosomonas)　in　TCS　pre-exposure　system　might　be　potential　hosts　of　ARGs.　This　study　might　provide　insights　for　better　understanding　the　fates　of　SUC　in　partial　nitrification　systems　and　the　ecological　risks　in　wastewater　containing　TCS　and　SUC.　Environmental　Implication:　Sucralose　(SUC)　is　often　detected　in　the　environment　and　considered　as　an　emerging　contaminant　due　to　its　soaring　consumption　and　environmental　persistence.　Triclosan　(TCS)　is　an　antibacterial　agent　that　often　co-exists　with　SUC　in　personal　care　products　and　sewage　environments.　During　150　d,　two　partial　nitrification　reactors　with　and　without　TCS　pre-exposure　were　established　to　study　the　effects　of　SUC　on　nitrification　performance,　antibiotic　resistance　genes　(ARGs)　and　microbial　communities.　This　study　showed　the　refractory　nature　of　SUC,　and　SUC　led　to　the　transmission　of　extracellular　ARGs　in　partial　nitrification　system　with　TCS　pre-exposure,　exacerbating　the　risk　of　ARGs　dissemination.　©　2023　Elsevier　B.V.