Alkali-activated　material　prepared　by　the　silicon　aluminum　solid　wastes　are　commonly　considered　as　the　low-carbon　cementitious　material,　which　has　important　significance　for　promoting　the　sustainable　development　of　construction　materials.　The　mechanical　properties,　reaction　mechanisms,　and　microstructure　evolutions　of　Alkali-activated　Ultra　High　Performance　Concrete　(AAUHPC)　matrix　with　7　design　parameters　were　comprehensively　studied　through　testing　the　fluidity,　28　days　compressive　strength,　28　days　flexural　strength,　hydration　heat,　and　microstructures.　The　environmental　impacts　including　carbon　emissions　and　energy　consumption　are　evaluated.　Appropriately　increasing　Na2O　dosage,　silicate　modulus　(Ms),　and　granulated　blast　furnace　slag　(GBFS)　to　fly　ash　(FA)　mass　ratio　(GBFS/FA)　and　decreasing　silica　fume　(SF)　content　and　water　to　binder　ratio　(W/B)　are　conducive　to　accelerating　the　early　reaction　of　AAUHPC.　High　Na2O　dosage,　Ms,　SF　content,　and　W/B　are　not　conducive　to　increasing　the　3　days　reaction　degree　of　AAUHPC,　while　the　moderate　GBFS/FA　is　corresponding　to　the　higher　3　days　reaction　degree　of　AAUHPC.　The　optimal　Na2O　dosage,　Ms,　GBFS/FA,　SF　content,　sand　to　binder　ratio　(S/B),　fine　sands　content　in　quartz　sands,　W/B　are　8　%,　1.4,　4.5:1,　10　%,　1.0,　50　%,　and　0.34　for　the　28　days　mechanical　properties.　The　acquired　AAUHPC　matrix　with　fluidity　of　218　mm　and　the　lowest　porosity　has　28　days　compressive　strength　of　114.8　MPa　and　28　days　flexural　strength　of　10.6　MPa,　whose　microstructure　has　more　high　polymerization　degree　C(N)-A-S-H　gels　with　higher　Al/Si,　lower　Na/Al,　and　lower　Ca/Si　molar　ratios.　Compared　to　the　traditional　Ultra　High　Performance　Concrete　(UHPC),　the　environmentally　friendly　AAUHPC　can　reduce　the　carbon　emission　by　42%-52　%　and　the　energy　consumption　by　5%-18　%.　The　total　CO2　emission　of　per　unit　compressive　strength　(1.0　MPa)　of　concrete　per　cubic　meter　(CI)　is　in　range　of　2.5-3.7　kg,　which　is　significantly　lower　than　the　traditional　UHPC　(6.98　kg/MPa　center　dot　m3).