Nuclear　magnetic　resonance　(NMR)　and　damage　impact　testing,　using　a　split　Hopkinson　pressure　bar　(SHPB)　technique,　were　conducted　on　weakly　weathered　granites　of　different　porosities.　Based　on　this,　this　study　determined　and　analysed　the　pore　structure　and　distribution,　propagation　characteristics　of　stress　waves,　changes　in　initial　tangent　modulus,　and　energy　dissipation　in　weakly　weathered　granites　of　different　porosities.　The　research　demonstrated　that　the　nature　of　the　internal　porosity　of　weakly　weathered　granites　changed　with　total　porosity.　Pore　structure　significantly　influenced　the　amplitude　of　reflected　waves　and　distortion　of　transmitted　waves.　Under　constant-damage　impact　loads,　the　initial　tangent　modulus　decreased　with　increasing　porosity,　whereas　the　stress-strain　curves,　after　reaching　the　peak　stress,　had　similar　shapes.　Peak　stress　and　average　strain　rate　showed　a　strong　power-law　correlation　with　porosity,　and　peak　stress　decreased　in　a　power-law　correlation　with　the　increase　of　average　strain　rate.　In　other　words,　the　difference　in　average　strain　resulted　from　different　porosities　when　the　incident　energy　was　same,　and　the　average　strain　was　negatively　correlated　with　porosity.　Under　damaging　impact,　the　energy　absorbed　per　unit　volume　decreased　with　increasing　porosity.　The　research　results　reveal　dynamic　characteristics　of　natural　porous　rocks　under　damage　impacts,　which　provide　a　reference　for　studying　damage　effects　of　porous　rocks　under　the　effects　of　stress　waves.