With　the　rapid　development　of　broadcasting,　communication　and　aviation　industry,　the　study　of　vacuum　electron　devices　has　become　the　key　issue　of　the　researchers　around　the　world　[1].　Being　the　heart　of　electron　tubes　and　magnetrons,　the　cathode　plays　an　important　role　in　these　devices.　Two　kinds　of　cathodes,　rare　earth　oxide-Mo　cermet　(RE2O3-Mo　in　brief)　secondary　emission　materials　and　Scandia　doped　tungsten　matrix　impregnated　thermionic　emission　materials　have　been　studied.　©　2010　IEEE.