The　chemical　state　of　lanthanum　on　the　surface　of　La2O3-Mo　cathode　and　its　role　in　the　emission　stability　improvement　were　analyzed.　Single　rate　earth　oxide　of　La2O3,　Y2O　3,　and　Sc2O3　or　a　mixture　of　the　oxides　doped　molybdenum　cathodes　were　produced　by　powder　metallurgy　method.　Computer　pattern　recognition　technique　was　used　to　optimize　the　composition　of　the　material　and　cathode　preparation　technique.　It　was　found　that　among　all　the　carbonized　samples　La2O3　and　Y2O3　co-doped　molybdenum　cathode　showed　the　best　performance　in　the　emission.