The　structures,　grain　sizes　and　magnetism　were　analyzed　and　computed　for　three　typical　samples:　the　stock　of　polycrystalline　metal　Gd　(sample　1),　the　bulk　nanocrystalline　Gd　prepared　by　spark　plasma　sintering　(SPS)　technique　and　subjected　to　the　annealing　process　of　623　K　for　0.5　h　(sample　2)　and　the　bulk　nanocrystalline　Gd　prepared　by　the　SPS　technique　at　573　K　(sample　3).　The　computation　results　indicated　that　the　sample　3　had　the　efficiency　of　space　filling　up　to　99.38%.　The　computation　results　of　magnetization　indicated　that　the　ferromagnetism　was　contributed　by　the　4f(7)　electrons　and　21%　of　the　5d(1)　itinerant　electrons　in　the　metal　Gd.　The　ferromagnetism　of　the　nanocrystalline　Gd　decreased　significantly　compared　with　the　stock　of　the　polycrystalline　Gd.　The　possible　reasons　are:　the　existence　of　a　small　quantity　of　the　Gd2O3　impurity,　and　the　existence　of　the　phase　of　antiferromagnetism　in　the　nanocrystalline　Gd.　The　curves　of　the　magnetic　susceptibility　X　which　are　dependent　on　the　temperature　T　of　the　samples　were　steep　in　the　vicinity　of　the　phase-transition　point　T-c.　It　was　determined　to　be　a　second-order　phase　transition　by　the　linear　relationship　between　the　reciprocal　of　the　magnetic　susceptibility　1/chi　and　temperature　T　by　the　analysis　of　Landau＇s　phase-transition　theory.