Hysteresis　loops　and　energy　products　have　been　calculated　systematically　by　a　three-dimensional　(3D)　software　OOMMF　for　Sm-Co/alpha-Fe/Sm-Co　trilayers　with　various　thicknesses　and　beta,　where　beta　is　the　angle　between　the　easy　axis　and　the　field　applied　perpendicular　to　the　film　plane.　It　is　found　that　trilayers　with　a　perpendicular　anisotropy　possess　considerably　larger　coercivities　and　smaller　remanences　and　energy　products　compared　with　those　with　an　in-plane　anisotropy.　Increase　of　beta　leads　to　a　fast　decrease　of　the　maximum　energy　product　as　well　as　the　drop　of　both　remanence　and　coercivity.　Such　a　drop　is　much　faster　than　that　in　the　single-phased　hard　material,　which　can　explain　the　significant　discrepancy　between　the　experiment　and　the　theoretical　energy　products.　Some　modeling　techniques　have　been　utilized　with　spin　check　procedures　performed,　which　yield　results　in　good　agreement　with　the　one-dimensional　(1D)　analytical　and　experimental　data,　justifying　our　calculations.　Further,　the　calculated　nucleation　fields　according　to　the　3D　calculations　are　larger　than　those　based　on　the　1D　model,　whereas　the　corresponding　coercivity　is　smaller,　leading　to　more　square　hysteresis　loops　and　better　agreement　between　experimental　data　and　the　theory.