The　mesoscopic　damage　characteristics　of　geopolymer　under　freezing-thawing　(F-T)　cycles　affect　its　macroscopic　physical　and　mechanical　properties,　which　further　influence　the　safety　of　geopolymer　buildings.　This　paper　presents　a　study　on　the　mesoscopic　damage　characteristics　of　hydrophobicity-modified　geopolymer　composites　(HM-GC)　based　on　the　CT　scanning　technique.　The　damage　degree　and　damage　distribution　characteristics　of　geopolymer　composites　(GC)　before　and　after　hydrophobic　modification　were　compared.　The　gradient　distribution　characteristics　of　damage　caused　by　F-T　cycles　in　HM-GC　were　further　analyzed.　The　results　show　that　the　volumetric　porosity　of　the　GC　is　always　larger　than　that　of　HM-GC　under　the　same　F-T　cycle　number,　indicating　the　hydrophobic　treatment　can　reduce　the　F-T　cycle　damage　rate　and　damage　degree.　The　results　also　show　that　the　damage　induced　by　F-T　cycles　in　GC　and　HM-GC　shows　obvious　spatial　gradient　characteristics.　As　the　F-T　cycle　number　increases,　the　average　gradient　coefficient　of　GC　increases　first　and　then　decreases,　while　the　average　gradient　coefficient　of　HM-GC　increases　first　and　then　stabilizes.　The　hydrophobic　treatment　can　reduce　the　gradient　characteristics　of　the　F-T　cycle　damage　and　improve　the　F-T　durability　of　geopolymer　composites.　©　2023　Elsevier　Ltd