Granite　powder　(GP)　and　active　mineral　admixture　including　ground　granulated　blast　furnace　slag　(GGBFS),　metakaolin　(MK)　and　fly　ash　(FA)　were　used　to　partially　replace　granite　manufactured　sand　(GMS)　and　cement　to　prepare　manufactured　sand　mortar　(MSM).　Synergistic　effect　of　four　mineral　admixtures　in　MSM　on　mechanical　properties,　water　absorption　properties　and　chloride　permeability　was　studied.　Combined　with　the　analysis　of　cementitious　materials　hydration　and　pore　characteristics,　the　synergistic　mechanism　of　four　mineral　admixtures　was　comprehensively　expounded.　The　results　show　that　although　the　synergy　of　GP　can　improve　the　performance　of　MSM,　the　replacement　of　cement　by　GGBFS　and　FA　leads　to　the　increase　of　water　absorption　and　chloride　diffusion　coefficient　and　the　decrease　of　mechanical　properties.　Synergistic　effect　of　GP,　GGBFS,　FA　and　MK　is　greater　than　that　of　the　three　of　them　due　to　the　complementarity　of　particle　size　and　chemical　composition　of　the　four　materials,　which　ends　the　situation　of　MSM　performance　reduction.