Benzethonium　chloride　(BZC)　is　a　type　of　quaternary　ammonium　compounds　(QACs),　which　could　flow　into　the　sewage　and　coexist　with　common　microplastics　(MPs),　potentially　causing　short-term　stress　to　wastewater　treatment　plants　(WWTPs).　This　study　carried　out　batch　experiments　to　explore　the　responses　of　the　anaerobic　ammonium　oxidation　(anammox)　system　to　single　and　combined　short-term　stress　of　different　concentrations　of　BZC　and　polyurethane　(PU)　MPs.　The　single　and　combined　short-term　stress　of　high　concentration　BZC　(5　mg/L)　exhibited　a　notable　inhibitory　impact　on　the　performance　of　the　anammox　system,　and　it　also　markedly　decreased　the　abundance　of　anammox　functional　genes　and　anammox　bacteria　(AnAOB).　Moreover,　the　shortterm　stress　of　5　mg/L　BZC　promoted　the　enrichment　of　resistance　genes　(RGs)　in　water　and　extracellular　RGs　in　sludge,　while　the　stress　of　PU　MPs　resulted　in　the　proliferation　of　mobile　genetic　elements　(MGEs)　in　sludge,　thus　increasing　the　risk　of　RGs　transmission.　This　research　focused　on　the　short-term　stress　of　BZC　and　PU　MPs　on　the　anammox　system　and　brought　new　insights　into　the　effects　of　BZC　and　PU　MPs　on　the　transmission　patterns　of　RGs　and　their　interactions　with　the　microbial　community.