By　utilizing　the　improved　split　Hopkinson　pressure　bar　(SHPB)　test　device,　uniaxial,　constant-speed　cyclic,　and　variable-speed　cyclic　impact　compression　tests　were　conducted　on　weakly　weathered　granite　samples.　By　combining　nuclear　magnetic　resonance　(NMR)　and　triaxial　seepage　tests,　this　study　investigated　the　change　laws　in　the　mechanical　properties,　porosity　evolution,　and　permeability　coefficients　of　the　samples　under　cyclic　impacts.　The　results　showed　that　in　constant-speed　cyclic　impacts　with　increasing　impact　times,　deformation　modulus　decreased,　whilst　porosity　firstly　decreased　and　then　increased.　Furthermore,　dynamic　peak　strength　firstly　increased　and　then　decreased　whereas　peak　strain　constantly　increased　before　failure　of　the　samples.　In　the　variable-speed　cyclic　impacts,　as　impact　times　increased,　deformation　modulus　firstly　increased　and　then　declined　with　damage　occurring　after　four　impact　times.　The　compaction　process　weakened　and　even　disappeared　with　increasing　initial　porosity.　Three　types　of　pores　were　found　in　the　samples　that　changed　in　multiscale　under　cyclic　loading.　In　general,　small　pores　extended　to　medium-　and　large-sized　pores.　After　three　variable-speed　cyclic　impacts,　the　porosity　of　the　samples　was　larger　than　the　initial　porosity　and　the　permeability　coefficient　was　greater　than　its　initial　value.　The　results　demonstrate　that　the　purpose　of　enhancing　permeability　and　keeping　the　ore　body　stable　can　be　achieved　by　conducting　three　variable-speed　cyclic　impacts　on　the　samples.