Comparisons　between　three　alkali-activators　(NaOH,　NaOH/Na2CO3,　water　glass)　on　the　performance　of　alkali-activated　nickel　slag　cementitious　materials　(ANC)　were　made.　The　properties　of　ANC,　including　setting　time,　mechanical　properties,　morphology　of　hydration　products　and　pore　structure　were　investigated　by　scanning　electron　microscope　(SEM),　X-ray　diffraction　(XRD)　and　nitrogen　adsorption　test　etc.　The　average　pore　size　and　total　pore　volume　of　water　glass-activated　system　(NS6)　are　the　smallest,　and　then　the　NaOH/Na2CO3-activated　system　(NN42),　and　the　average　pore　size　and　total　pore　volume　of　NaOH-activated　system　(NH6)　are　the　largest.　Interfacial　transition　zone　(ITZ)　between　aggregate　and　hardened　cement　paste　(HCP)　decreased　from　large　to　small　is　in　the　order　of　NS6　＞　NN42　＞　NH6.　The　microcracks　of　NS6　in　HCP　is　most　obvious,　and　then　the　NH6,　and　the　microcracks　of　NN42　in　HCP　is　least　obvious.　The　pore　structure　and　ITZ　play　dominated　role　on　mechanical　properties,　and　therefore　the　compressive　and　flexural　strengths　of　alkali-activated　nickel　slag　mortar　are　ranked　from　large　to　small　in　the　order　of　NS6　＞　NN42　＞　NH6.　(C)　2019　Elsevier　Ltd.　All　rights　reserved.