As　the　cathode　with　the　highest　electron　emission　capability　in　the　thermionic　cathode,　the　scandate　cathode　has　attracted　more　and　more　attention　in　recent　years,　especially　the　scandia　doped　tungsten　matrix　scandate　cathode.　Experimental　studies　show　that　scandia　doped　tungsten　matrix　scandate　cathodes　with　submicron　microstructures　exhibit　excellent　emission　capacity,　and　the　pulse　emission　current　density　in　the　space-charge　region　can　be　over　35　A　cm(-2)　at　850　degrees　C-b.　In　the　direct　current　(DC)　condition　with　temperature　compensation,　the　emission　current　density　could　reach　25　A　cm(-2)　at　850　degrees　C-b.　The　device　lifetime　is　over　3700　h　after　operating　at　950　degrees　C-b　with　the　DC　loading　of　40　A　cm(-2).　The　emission　mechanism　of　the　scandate　cathode　including　the　effect　of　the　surface　structure　and　composition　on　the　work　function　of　the　cathode　are　systematically　reviewed.