The　effects　of　typical　disinfectants　chloroxylenol　(PCMX)　and　benzethonium　chloride　(BEC)　on　heterotrophic/　sulfur　autotrophic　denitrification　(HSAD)　systems　under　single　and　mixed　stress　were　studied.　PCMX　increased　the　system＇s　denitrification　activity,　but　BEC　and　mixed　disinfectants,　particularly　mixed　disinfectants,　significantly　reduced　denitrification　activity.　PCMX　elevated　the　content　of　extracellular　polymeric　substances　(EPS)　in　HSAD　system,　and　the　structure　of　EPS　was　tight　and　stable.　Whereas　the　other　two　systems　had　lower　EPS　content　and　looser　structure,　highlighting　the　greater　damaging　effects　of　BEC　and　mixed　disinfectants.　PCMX　led　to　the　enrichment　of　more　than　half　of　the　resistance　genes　(RGs),　while　mixed　disinfectants　resulted　in　the　fewest　RGs　enriched　and　the　lowest　correlations　between　bacteria　and　RGs　of　three　systems.　The　transformation　of　extracellular　qacE　was　induced　by　PCMX.　BEC　caused　RGs　to　leak　out　of　bacteria,　and　mixed　disinfectants　contributed　to　transformation　and　efflux　of　RGs.　PCMX　increased　the　abundance　of　Thiobacillus　and　Sulfurimonas.　Thiobacillus　was　more　abundant　in　low　doses　of　BEC　and　mixed　disinfectants,　but　it　reduced　at　high　concentrations,　while　the　amount　of　Sulfurimonas　continued　to　decrease.　This　study　provided　an　insight　into　the　effects　of　single　and　mixed　disinfectants　on　HSAD　systems,　and　guided　future　efforts　to　control　disinfectants　and　RGs　pollution　in　wastewater　treatment.