The　damage　monitoring　of　geopolymers　in　cold　regions　is　important　to　ensure　their　durability.　This　paper　presents　an　investigation　on　the　damage　evaluation　of　geopolymer　under　three　freezing-thawing　treatments　with　different　freezing　temperatures　based　on　an　ultrasonic　technique.　Firstly,　95　metakaolin-based　geopolymer　specimens　were　prepared　and　subjected　to　freezing-thawing　(F-T)　cycles　under　five　freezing　temperatures　(−1.0　°C,　−10.0　°C,　−20.0　°C,　−30.0　°C,　−40.0　°C)　by　three　F-T　treatments,　which　are　freezing　in　air　and　thawing　in　water　(A-W),　freezing　in　water　and　thawing　in　water　(W–W)　and　freezing　and　thawing　in　air　(A-A),　respectively.　Secondly,　the　nondestructive　ultrasonic　tests　were　used　to　monitor　the　degradation　of　the　geopolymer　during　F-T　cycles　and　uniaxial　compressive　strength　tests　were　conducted　to　study　the　residual　strength　of　geopolymer　after　F-T　cycles.　Thirdly,　the　effects　of　freezing　temperature　and　F-T　treatment　on　the　longitudinal　wave　velocity　and　ultimate　compressive　strength　were　analyzed.　Finally,　a　nondestructive　method　was　proposed　to　predict　the　compressive　strength　of　geopolymer　after　F-T　cycles.　The　results　showed　that　the　longitudinal　wave　velocity,　dynamic　elastic　modulus　and　uniaxial　compressive　strength　of　geopolymer　all　decrease　as　the　freezing　temperature　decreases.　The　damage　difference　of　geopolymer　under　three　F-T　treatment　methods　gradually　increases　as　the　freezing　temperature　decreases.　Compared　with　W–W　method　and　A-A　method,　the　geopolymer　under　A-W　treatment　method　showed　the　most　serious　deterioration.　The　results　also　showed　that　the　compressive　strength　damage　and　longitudinal　wave　velocity　damage　exhibited　exponential　relations.　The　nondestructive　method　based　on　longitudinal　wave　velocity　can　efficiently　predict　the　damage　evaluation　of　geopolymer　under　different　F-T　treatments　and　freezing　temperatures.　©　2023　Elsevier　Ltd