Biofilters　inoculated　with　activated　sludge　are　widely　used　for　odor　control　in　WWTP.　In　this　process,　biofilm　community　evolution　plays　an　important　role　in　the　function　of　reactor　and　is　closely　related　to　reactor　per-formance.　However,　the　trade-offs　in　biofilm　community　and　bioreactor　function　during　the　operation　are　still　unclear.　Herein,　an　artificially　constructed　biofilter　for　odorous　gas　treatment　was　operated　for　105　days　to　study　the　trade-offs　in　the　biofilm　community　and　function.　Biofilm　colonization　was　found　to　drive　community　evolution　during　the　start-up　phase　(phase　1,　days　0-25).　Although　the　removal　efficiency　of　the　biofilter　was　unsatisfactory　at　this　phase,　the　microbial　genera　related　to　quorum　sensing　and　extracellular　polymeric　sub-stance　secretion　led　to　the　rapid　accumulation　of　the　biofilm　(2.3　kg　biomass/m3　filter　bed　/day).　During　the　stable　operation　phase　(phase　2,　days　26-80),　genera　related　to　target-pollutant　degradation　showed　increases　in　relative　abundance,　which　accompanied　a　high　removal　efficiency　and　a　stable　accumulation　of　biofilm　(1.1　kg　biomass/m3　filter　bed/day).　At　the　clogging　phase　(phase　3,　days　81-105),　a　sharp　decline　in　the　biofilm　accumulation　rate　(0.5　kg　biomass/m3　filter　bed　/day)　and　fluctuating　removal　efficiency　were　observed.　The　quorum　quenching-related　genera　and　quenching　genes　of　signal　molecules　increased,　and　competition　for　re-sources　among　species　drove　the　evolution　of　the　community　in　this　phase.　The　results　of　this　study　highlight　the　trade-offs　in　biofilm　community　and　functions　during　the　operation　of　bioreactors,　which　could　help　improve　bioreactor　performance　from　a　biofilm　community　perspective.