The　influence　of　the　charged　surfaces　of　non-conducting　materials　(such　as　ceramic　Al2O3)　and　the　atmospheric　pressure　on　X-ray　energy　dispersive　spectroscopy　(EDS)　analysis　with　environmental　scanning　electron　microscopy　(ESEM)　was　experimentally　studied.　And　the　appropriate　compensation　and　corrections　were　proposed.　We　found　that　in　high　vacuum,　the　charge　effect　increases　the　oxygen　contents　in　EDS　spectrum,　and　that　the　EDS　errors　can　be　reduced　by　lowering　the　pressure　because　low　vacuum　eliminates　the　charge　effect　and　decreases　the　surface　potential.　The　X-ray　pressure　limit　aperture　(PLA)　can　further　reduce　the　errors　by　weakening　the　beam　skirt　scattering.　The　scattering　of　both　the　electron　and　the　low　energy　X-ray　by　higher　pressure,　accounts　for　the　large　EDS　errors.