Rare-earth　tungsten　thermionic　emission　material　was　used　in　the　high-temperature　electrostatic　dust　removal　technology.　A　static　test　facility　was　self-designed　to　explore　the　emission　characteristic.　XRD,　SEM　and　EDS　were　used　to　analyze　the　microstructure　and　element　distribution.　Working　in　high-temperature　and　oxidizing　condition,　tungsten　in　the　thermionic　emission　materials　is　oxidized　to　tungsten　trioxide,　but　the　rare-earth　tungstate　in　the　grain　boundary　has　no　chemical　changes.　In　high-temperature　and　oxidizing　ambience,　there　is　oxidation　and　volatilization　on　the　surface　of　rare-earth　tungsten,　resulting　in　materials　loss.　The　degree　of　loss　depends　on　the　composition　of　gas.