The　work　functions　of　the　(110)　and　(100)　surfaces　of　LaB6　are　determined　from　ambient　pressure　to　39.1GPa.　The　work　function　of　the　(110)　surface　slowly　decreases　but　that　of　the　(100)　surface　remains　at　a　relatively　constant　value.　To　determine　the　reason　for　this　difference,　the　electron　density　distribution　(EDD)　is　determined　from　high-pressure　single-crystal　x-ray　diffraction　data　by　the　maximum　entropy　method.　The　EDD　results　show　that　the　chemical　bond　properties　in　LaB6　play　a　key　role.　The　structural　stability　of　LaB6　under　high　pressure　is　also　investigated　by　single-crystal　x-ray　diffraction.　In　this　study,　no　structural　or　electronic　phase　transition　is　observed　from　ambient　pressure　to　39.1GPa.