Nanocrystalline　nickel　with　grain　size　of　20nm　was　prepared　by　pulse　electrodeposition.　The　thermal　stability　was　studied　by　transmission　electron　microscopy　(TEM),　X-ray　diffraction　(XRD)　and　thermal　analysis.　The　results　show　that　the　grains　of　Ni　depositions　begin　to　grow　obviously　at　about　255°C,　and　the　grain　growth　process　during　the　heating　includes　two　stages:　low　temperature　abnormal　grain　growth　(200-300°C)　and　normal　grain　growth　(300-500°C).　The　original　(111)　and　(200)　double　fibre　texture　still　exist　at　low　temperature　grain　growth　stage,　but　diminish　gradually　at　normal　grain　growth　stage.　The　microhardness　of　Ni　depositions　increases　slightly　at　100°C,　and　then　decreases　with　the　increasing　the　heating　temperature.