Binary　rare　earth　hexaborides　(REB6)　have　different　rare　earth　elements　with　different　valence　electron　distributions,　which　lead　to　different　strange　physical　properties　and　different　emission　properties.　However,　in　the　electron　emission　properties,　whether　PrB6,　NdB6,　SmB6　and　GdB6　all　have　excellent　emission　properties　remains　to　be　further　studied,　and　the　physical　mechanism　affecting　their　emission　properties　needs　investigating.　In　this　paper,　the　electronic　structures,　work　functions　of　typical　binary　single　crystal　REB6　(LaB6,　CeB6,　PrB6,　NdB6,　SmB6,　GdB6)　are　studied　by　first　principles　calculations.　The　single　crystal　REB6　are　prepared　by　optical　zone　melting　method,　and　their　thermionic　electron　emission　properties　are　tested　experimentally.　The　theoretical　calculation　results　show　that　the　typical　binary　REB6　have　large　densities　of　states　near　the　Fermi　level.　The　d-orbitals　with　broad　distributions　in　conduction　bands　are　beneficial　to　electron　emission.　The　localized　f-orbital　electrons　in　valence　bands　are　not　conducive　to　their　electron　emission.　The　theoretical　calculations　of　work　functions　of　typical　binary　single　crystal　REB6　(100)　surface　are　consistent　with　the　analyses　of　their　electronic　structures.　The　theoretical　calculation　values　of　work　functions　are　ordered　as　GdB6　(2.27　eV)　＜　CeB6　(2.36　eV)　＜　LaB6　(2.40　eV)　＜　PrB6　(2.58　eV)　＜　SmB6　(2.63　eV)　＜　NdB6　(2.91　eV).　The　experimental　test　results　of　thermionic　electron　emission　of　single　crystal　show　that　the　experimental　thermionic　electron　properties　are　consistent　with　the　theoretical　ones.　The　LaB6　and　CeB6　both　have　good　thermionic　and　field　emission　properties,　and　the　GdB6　has　excellent　field　emission　properties.