This　paper　investigated　the　impacts　of　pore　structure　characteristics　on　pore　water　freezing　of　sandstone　at　low　temperatures.　Freeze–thaw　cycles　(from　−　20.0　to　20.0　℃)　were　conducted　to　change　the　pore　structure　of　sandstone　using　two　different　freeze–thaw　treatment　methods.　Multi-level　freezing　treatments　(–　1.5　℃,　–　4.0　℃,　–　6.0　℃,　–　10.0　℃,　–　15.0　℃　and　–　20.0　℃)　and　nuclear　magnetic　resonance　(NMR)　tests　were　performed　to　study　the　evolution　of　unfrozen　water　content　(UWC)　of　sandstone　with　temperature　and　analyze　the　evolution　difference　caused　by　pore　sizes.　The　impacts　of　pore　structure　characteristics,　such　as　porosity,　pore　size　distribution　and　fractal　dimension,　on　the　UWC　at　different　temperatures　were　discussed.　Moreover,　a　prediction　model　based　on　porosity　was　proposed　for　estimating　the　frozen　degree　of　pore　water　of　sandstone　at　low　temperatures.　The　results　indicate　that　with　decreasing　temperature,　the　pore　water　in　sandstone　undergoes　supercooling　stage　(0.0 to – 1.3　℃),　rapid　freezing　stage　(–　1.3　to　–　4.1　℃)　and　slow　freezing　stage　(–　4.1　to　–　20.0　℃).　However,　the　pore　water　freezing　is　affected　by　pore　sizes,　with　the　UWC　of　micropores　decreasing　gradually　with　decreasing　temperature,　while　that　of　minipores　and　mesopores　first　decreasing　sharply　and　then　remaining　approximately　constant.　Interestingly,　significant　correlations　are　observed　between　UWC　and　parameters　such　as　porosity,　micropore　content,　mesopore　content　and　fractal　dimension,　suggesting　their　potential　in　evaluating　pore　water　freezing.　Furthermore,　the　proposed　model　can　effectively　predict　the　frozen　degree　of　pore　water　in　sandstone　at　low　temperatures　with　an　acceptable　error.　©　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Austria,　part　of　Springer　Nature　2025.