The　erosion　resistance　of　alpha-Al2O3　ceramics　in　flowing　suspensions　of　solid　particles　was　investigated　with　a　rotary　disk　erosion　wear　tester.　The　effect　of　different　abrasive　particle　hardness　on　its　erosion　resistance　was　studied　and　the　microcosmic　failure　mechanism　of　its　surface　was　analyzed.　The　results　show　that　the　erosion　resistance　of　alpha-Al2O3　is　more　and　more　excellent　than　that　of　the　metal　Cr15Mo3　with　the　hardness　enhancement　of　the　abrasive　particles.　When　SiO2,　Al2O3,　SiC　is　in　turn　selected　as　the　abrasive,　the　erosion　resistance　of　alpha-Al2O3　ceramics　is　4.06,　5.20,　5.77　times　than　that　of　Cr15Mo3　respectively　due　to　the　different　hardness　of　such　abrasives.　Due　to　erosion,　Cr15Mo3　is　worn　out　most　in　the　whole,　the　erosion　holes　are　very　clear　and　its　failure　pattern　is　in　＂W＂　shape.　The　wear　of　alpha-Al2O3　mainly　occurs　in　the　binding　phase　of　the　crystal　boundary　for　its　grain　is　fine　and　dense　enough.　So　although　the　crystal　grains　are　exposed　at　last,　no　breaks　and　cracks　can　be　found　on　the　erosion　surface.　Its　failure　pattern　is　in　＂U＂　shape.