An　operating　model　for　scandate　cathode　with　fine　sub-micro　structure　Sc2O3　doped　W　bodies　was　discussed.　High　mixing　quality　of　Sc2O3　doped　W　bodies　were　made　by　a　liquid-liquid　doping　technique　and　carefully　controlled　pressing　and　sintering　procedures.　During　activation,　the　accumulation　of　Sc　on　surface　was　ascribed　to　diffusion　from　interior　body　with　Ba　and　O.　A　multi-layer　of　Ba-Sc-O　was　formed　on　surface　of　this　kind　of　cathode,　which　is　in　the　close　relationship　with　its　emission　properties.