The　mechanical　performance　of　concrete-filled　steel　tubular　(CFST)　members　could　be　affected　by　the　debonding　gaps　between　steel　tubes　and　core　concrete.　In　this　paper,　the　finite　element　models　(FEMs)　of　axially　loaded　CFST　stub　columns　with　different　debonding　gap　types,　i.e.,　circumferential　debonding　gap　(CDG)　or　spherical-cap　debonding　gap　(SDG),　were　implemented　by　ABAQUS.　The　accuracy　of　FEMs　was　verified　by　test　results.　The　influence　of　different　debonding　gap　types　on　the　mechanical　performance　of　axially　loaded　CFST　stub　columns　with　the　same　debonding　cross-sectional　area　was　compared　by　using　FEMs.　The　results　showed　that　compared　with　SDG,　the　influence　of　CDG　on　the　ultimate　load-bearing　capacity　(Nu)　was　larger　and　on　the　failure　mode　was　smaller.　With　an　increase　in　CDG　arc-length　ratio　(RCDG),　the　reduction　coefficient　of　Nu　(KD)　firstly　increased　and　then　decreased.　With　an　increase　in　SDG　ratio　(χSDG),　the　KD　decreased.　With　an　increase　in　RCDG　or　χSDG,　the　Nu　decreased.　All　the　debonding　specimens　showed　inward　buckling　in　steel　tubes　within　the　debonding　range,　while　the　outward　lateral　deflection　towards　the　no-debonding　range　was　also　observed.　With　an　increase　in　RCDG,　the　inward　buckling　of　steel　tubes　was　more　severely　to　contact　with　the　core　concrete　at　the　middle-height　of　columns,　then　an　outward　buckling　was　found.　With　an　increase　in　χSDG,　the　inward　buckling　of　steel　tubes　become　more　significant,　but　the　failure　modes　remained　unchanged.　©　IABSE　Congress　Nanjing　2022　-　Bridges　and　Structures:　Connection,　Integration　and　Harmonisation,　Report.　All　rights　reserved.