Y2O3-MO　cermet　cathodes　were　prepared　by　mechanical　mixing　of　Y2O3　and　Mo　powder.　The　prepared　cermet　cathode　provides　a　certain　secondary　emission　yield　(3.09),　about　1.8　times　lower　than　that　for　the　cathode　prepared　by　sol-gel　method.　It　was　found　that　the　cathode　prepared　by　sol-gel　method　had　a　smaller　grain　size,　which　could　be　attributed　to　its　higher　emission　property.　The　energy　distributions　of　primary　electrons　in　the　cathodes　with　different　grain　sizes　have　been　simulated　by　Monte　Carlo　method.　Based　on　the　calculation　results,　the　emission　models　of　the　cathodes　are　established　and　presented.　The　cathodes　with　different　grain　sizes　exhibited　different　ways　of　emission.　Two　types　of　emission,　of　reflection　emission　and　transmission　emission,　existed　in　the　cathode　with　small　grain　sizes　whereas　only　transmission　emission　existed　in　the　cathode　with　large　grain　sizes.　(C)　2009　Elsevier　Ltd.　All　rights　reserved.