Rapid　trace　gas　identification　is　challenging　due　to　the　low　adsorptivity　of　gaseous　molecules　on　solid　substrates　under　ambient　conditions.　In　this　article,　we　present　a　gas　sensor　utilizing　a　capillary　serving　as　a　surface-enhanced　Raman　scattering　(SERS)　probe.　The　capillary　is　decorated　with　densely　distributed　Ag/ZnO　nanocomposites　within　its　microchannel,　resulting　in　an　enlarged　specific　surface　area　that　enhances　gas　adsorption　and　chemical　enhancement　and　provides　abundant　SERS　hotspots.　The　introduction　of　gas　into　the　capillary　leads　to　the　immediate　appearance　of　distinctive　Raman　characteristic　peaks,　and　the　entire　measurement　process　can　be　performed　under　ambient　conditions.　The　detection　limit　for　gases　of　NO2　and　SO2　reaches　as　low　as　0.1　ppb.　Furthermore,　the　sensor　exhibits　the　capability　to　identify　components　of　mixed　gases　as　well　as　effectively　detect　NO2　in　vehicle　exhaust　emissions.　With　all　of　these　advantages,　the　SERS-active　capillary　demonstrates　promising　potential　for　practical　applications,　particularly　in　the　rapid　and　accurate　identification　of　trace-level　gases.