Crack　width　can　directly　represent　the　damage　characteristics　of　structural　components，and　it　is　an　important　index　for　seismic　damage　assessment.　In　view　of　the　many　shortcomings　in　the　calculation　methods　and　measurement　of　crack　width，considering　a　variety　of　influence　factors，a　calculation　method　of　diagonal　crack　width　based　on　the　bond-slip　theory　is　proposed.　In　view　of　the　uncertain　load　and　the　unaccurate　calcula⁃　tion　of　crack　width　of　the　member　in　service，the　calculation　method　and　flow　chart　of　transverse　crack　and　oblique　crack　width　of　reinforced　concrete（RC）column　based　on　bending　deformation　and　shear　deformation　are　presented.　On　this　basis，considering　the　real　state　of　the　RC　column　under　the　axial-flexure-shear　interaction　in　earthquake，the　theoretical　relationship　between　the　displacement　and　the　crack　width　is　established，and　the　method　and　process　of　calculating　the　maximum　crack　width　according　to　the　total　horizontal　displacement　is　pro⁃　posed.　The　experimental　results　show　that　the　maximum　crack　width　of　the　RC　column　calculated　by　the　pro⁃　posed　method　is　accurate　and　can　reveal　the　dynamic　evolution　process　of　the　crack　width　with　the　increase　of　displacement　under　the　state　of　axial-flexure-shear　interaction.　In　addition，the　failure　mode　of　RC　column　can　be　judged　according　to　the　numerical　ratio　of　transverse　crack　and　oblique　crack.　©　2023　Nanjing　University　of　Aeronautics　an　Astronautics.　All　rights　reserved.