Concrete-filled　steel　tubular　(CFST)　columns　are　frequently　used　as　the　main　load-bearing　components　in　engineering　structures　due　to　their　excellent　load-bearing　capacity.　However,　the　presence　of　steel　tube　makes　it　impossible　to　accurately　detect　the　damage　characteristics　of　concrete　by　only　relying　on　traditional　mechanical　measurement　methods.　This　article　quantitatively　investigates　the　concrete　damage　of　circular　CFST　column　during　axial　compression　based　on　the　acoustic　emission　(AE)　technique.　Through　the　cumulative　AE　parameters　including　amplitude,　count,　and　energy,　the　axial　compression　process　of　the　CFST　column　can　be　divided　into　five　main　stages　(Stage　I　is　divided　into　two　substages)　to　represent　the　different　damage　degree.　The　damage　characteristics　of　concrete　at　each　stage　were　explained　by　combining　AE　results　and　mechanical　phenomena.　A　sensitivity　analysis　of　the　axial　compression　process　was　carried　out　using　the　Historic　Index　(HI)　and　Severity　(Sr)　and　found　that　the　sudden　rise　in　HI　and　Sr　corresponded　to　the　changes　in　the　different　loading　stages.　The　Improved　b　(Ib)　value　analysis　calculated　from　the　AE　amplitudes　reflects　the　evolution　mechanism　of　the　crack　and　can　be　used　for　the　identification　of　the　final　failure　moment　of　the　specimen.　Finally,　a　new　method　for　processing　and　analyzing　AE　parameters　was　proposed,　which　effectively　enhanced　the　dimensionality　of　real-time　monitoring　information　on　the　damage　of　concrete　filled　in　the　steel　tube.