There　is　a　concern　that　continuous　alternating　exposure　to　disinfectants　will　affect　microbial　colonization　and　exacerbate　the　spread　of　resistance　genes　(RGs)　on　microplastics　(MPs)　biofilms.　In　this　study,　polyethylene　(PE)　and　polyethylene　glycol　terephthalate　(PET)　MPs　were　investigated　as　vectors　for　microbial　and　RGs　in　partial　nitrification-anammox　(PNA)　systems　under　different　disinfectant　exposure　modes.　Results　showed　that　ammonia-oxidizing　bacteria　Nitrosomonas　and　anammox　bacteria　Candidatus　Kuenenia　were　enriched　on　PE　MPs　and　PET　MPs.　Meanwhile,　the　abundance　of　Nitrosomonas　decreased　after　dioctadecyldimethylammonium　chloride　(DODMAC)　exposure　in　the　CD　system　(DODMAC　exposure　only),　but　was　instead　enriched　after　disinfectant　replacement　exposure　in　the　PD　system　(successively　exposed　to　chloroxylenol　(PCMX)　and　DODMAC)　and　TD　system　(successively　exposed　to　triclosan　(TCS)　and　DODMAC).　Oligotyping　analyses　showed　that　disinfectant　replacement　exposure　leads　to　differentiation　of　nitrogen　removal　functional　bacteria　and　pathogenic　bacteria　into　distinct　oligotypes.　The　RGs　were　found　to　be　enriched　in　PD　and　TD　systems　than　in　CD　system,　which　suggested　that　PCMX/TCS　and　DODMAC　replacement　exposure　increased　the　risk　of　RGs　spread.　In　addition,　quaternary　ammonium　compounds　RGs　(QRGs),　tended　to　be　enriched　more　on　PE　MPs　in　the　PD　system,　whereas　in　the　TD　system,　QRGs　were　enriched　more　on　PET　MPs.　In　summary,　the　MPs　increased　risk　of　RGs　spread　with　different　disinfectant　replacement　exposure　in　PNA　systems.