In　this　study,　a　kind　of　nickel　coated　carbon　nanotubes　(Ni-CNTs)　reinforced　pure　magnesium　(Mg)　matrix　composite　was　prepared　using　two-step　process.　The　nano-Mg2Ni　phase　at　the　interface　was　in-situ　formed　to　improve　the　interface　bonding　between　CNTs　and　Mg　matrix.　Results　indicated　that　the　yield　and　ultimate　tensile　strength　of　2.0　wt.　%　Ni-CNTs/Mg　composite　were　278.3　MPa　and　304.5　MPa,　respectively,　showing　77%　and　48%　increase　in　comparison　with　those　of　2.0　wt.　%　CNTs/Mg　composite.　The　remarkably　enhanced　mechanical　properties　were　attributed　to　the　strong　interface　bonding　due　to　the　in-situ　formed　nano-Mg2Ni　phase.　The　corresponding　strengthening　mechanisms　were　regarded　as　the　coupling　interface　effect　of　the　coherent　interface　and　the　interstitial　solid　solution.　Moreover,　the　CNTs　acted　as　a　bridging　role　in　load　transfer　and　obstructed　the　growth　of　cracks　in　Ni-CNTs/Mg　composites.　(C)　2017　Elsevier　B.V.　All　rights　reserved.