Microwave-LN2　cyclic　processing　(MLCP)　is　a　clean　and　high-efficiency　anhydrous　fracturing　technology.　The　change　in　the　porous　structure　of　coal　after　freeze-thaw　cycles　significantly　affects　development　efficiency　of　coalbed　methane　(CBM)　in　low　porosity　and　permeability　reservoirs,　while　there　is　a　lack　of　in-depth　macromeso-micro　studies.　The　damage　mechanism　of　coal　under　microwave-LN2　cold　and　thermal　shock　and　the　evolution　of　pore　fluid　reservoir　space　is　based　on　cross-scale　pore　characterisation.　This　paper　evaluates　the　multi-scale　porous　structure　variations　of　coal　before　and　after　MLCP　was　assessed　by　hydrogen　nuclear　magnetic　resonance　(1H　NNR)　and　field　emission　scanning　electron　microscopy　(FE-SEM).　The　evolutionary　trends　in　coal　pore　fluid　fugacity　space　under　freeze-thaw　cycles　was　indirectly　characterised　by　T-1　-T-2　spectra.　Additionally,　utilizing　T-2　distribution,　peak　area　and　pore　throat　changes　reflect　the　evolution　trend　of　coal　pore　space.　The　results　indicate　that　as　the　cycles　increased,　the　coal　free　water　and　total　fluid　reservoir　space　gradually　expanded　beyond　the　cycle　threshold　(n　＞　10),　the　free-fluid　index　rose　to　25.68　%,　and　the　free　fluid　saturation　increased　by　20.39　%.　Additionally,　the　NMR　permeability　of　the　coal　increased　by　98.37-1471.65　%,　and　the　pore　throat　distribution　increased　by　28.05　%.　Comprehensive　analysis　showed　that　as　the　cycles　progressed,　the　free　water　space　in　the　pore　space　increased　significantly,　the　proportion　of　bound　water　gradually　decreased,　and　the　internal　pores　and　fluid　space　of　the　coal　were　improved.　This　study　provides　fundamental　support　for　multidimensional　evaluation　of　the　porous　structure　of　microwave-LN2　freeze-thaw　cycles.