The　granite　powder　(GP)　was　used　to　partially　replace　granite　manufactured　sand　(GMS)　to　prepare　cement　mortar　in　this　study.　The　hydration　activity　and　the　influence　of　GP　on　cement　hydration　were　evaluated　by　isothermal　calorimetry.　The　effects　of　GP　substitution　ratio　on　porosity,　pore　distribution　and　capillary　water　absorption　coefficient　were　studied　by　vacuum　saturation,　X-ray　computed　tomography　(X-CT),　mercury　intrusion　porosimetry　(MIP)　and　capillary　water　absorption,　respectively.　The　relational　equation　between　capillary　water　absorption　coefficient　and　porosity　was　established　through　regression　analysis.　The　results　show　that　GP　as　an　inert　material　can　promote　the　hydration　of　cement.　The　porosity　and　capillary　water　absorption　coefficient　decrease　with　the　increase　of　GP　substitution　ratio.　The　preliminary　results　reported　in　this　paper　open　a　new　door　for　the　sustainable　application　of　GP　in　cementitious　materials　with　improved　performances.