Tetrapod-shaped　ZnO　nanomaterial　field　emission　cathode　was　prepared　by　deposition　method.　To　the　high-vacuum　flat　capsulation　with　phosphor　screen　and　cathode　was　applied　a　voltage　to　test　the　cathode　emission　current　and　the　phosphor　screen　brightness.　For　the　cathode　with　total　area　13　×　15　cm2,　the　test　results　showed　that　when　the　volume　percentage　of　K2SiO3　ranged　from　5.0　×　10-3　to　8.3　×　10-3,　concentration　of　Ba(NO3)2　arranged　from　5.0　×　10-4　to　7.7　×　10-4　M,　and　concentration　of　tetrapod-shaped　ZnO　arranged　from　8.2　×　10-4　to　1.2　×　10-3　M,　the　cathode　emission　current　was　the　largest,　and　phosphor　screen　at　peak　brightness　could　reach　60　cd/cm2.　The　average　brightness　was　48　cd/cm2.