Immobilized　fillers　have　been　increasingly　utilized　in　biotrickling　filters　(BTFs)　due　to　their　positive　impact　on　shock　load　resistance　and　recovery　performance.　However,　due　to　the　inherent　characteristics　of　its　immobilized　carrier,　the　immobilized　filler　is　prone　to　swelling　during　the　long-term　operation　of　the　system,　resulting　in　increased　pressure　drop.　Polyurethane　(PU)　sponge　was　used　as　the　cross-linked　skeleton　of　immobilized　filler　and　compared　with　direct　emulsified　cross-linked　immobilized　filler　for　treating　ethylbenzene　gas.　In　the　early　stage,　both　fillers　can　maintain　good　performance　despite　changes　in　the　inlet　concentration　and　short-term　stagnation.　However,　on　the　107th　day　of　operation,　the　immobilized　filler　experienced　swelling,　and　the　pressure　drop　sharply　increased　to　137.2　Pa,　while　the　PU　immobilized　filler　was　still　able　to　maintain　a　low-pressure　drop　level.　The　results　of　the　microbial　diversity　analysis　revealed　that　the　microbial　community　structure　of　PU　immobilized　fillers　remained　relatively　stable　when　responding　to　the　fluctuations　in　operating　conditions.　PU　sponges　as　the　skeleton　can　effectively　prolong　the　service　life　of　the　immobilized　filler　and　improve　the　performance　of　the　biotrickling　filter.