The　utilization　of　biomass　energy　is　attracting　worldwide　attention　due　to　the　worsening　energy　crisis　and　the　concerns　on　carbon　dioxide　emission.　However,　the　rapidly　development　of　biomass-fired　power　plants　generate　enormous　amount　of　slag　and　ash.　At　present,　the　main　treatment　method　of　biomass　slag　and　ash　is　landfill,　which　not　only　requires　high　cost,　but　also　causes　a　series　of　environmental　issues.　Aiming　at　this　problem,　the　slag　and　fly　ash　from　four　biomass　power　plants　were　sampled　and　characterized.　The　major/trace　element　composition　and　leaching　characteristics　of　slag　and　fly　ash　are　analyzed,　and　the　effect　of　volatile　mineral　in　these　solid　residues　on　furnace　efficiency　is　also　evaluated.　The　results　indicate　that　for　biomass-　fired　grate　furnaces,　in　the　generated　solid　residues,　the　slag　accounts　60　similar　to　70%　while　the　fly　ash　accounts　for　30　similar　to　40%.　The　volatile　elements　in　slag　are　much　lower　than　those　in　fly　ash,　and　the　unburned　carbon　content　of　fly　ash　is　generally　lower　than　that　of　slag.　Due　to　the　enrichment　of　volatile　minerals　in　fly　ash,　instead　of　815　degrees　C,　550　degrees　C　is　suggested　to　measure　the　unburned　carbon　content　in　fly　ash.　When　the　measuring　temperature　of　unburned　carbon　decreases　from　815　degrees　C　to　550　degrees　C,　the　measured　energy　loss　from　the　incomplete　combustion　of　solid　fuels　decreases　by　one　third,　which　affords　a　more　reasonable　evaluation　on　combustion　efficiency.　The　contents　of　cadmium　and　lead　in　certain　fly　ash　samples　exceed　the　standard,　however,　all　fly　ash　samples　have　a　high　leaching　rate　of　potassium　but　low　leaching　rates　of　copper,　zinc,　cadmium,　lead,　chromium　and　arsenic.　It　indicates　that　the　fly　ash　from　biomass-fired　grate　furnace　is　suitable　for　producing　potassium　fertilizer　by　leaching　instead　of　direct　soil　fertilization　or　landfill.　The　leaching　rate　of　most　minerals　in　slag　is　much　lower　than　that　in　fly　ash　and　the　contents　of　heavy　metals　are　far　below　the　prescribed　upper　limit　in　standard,　which　indicates　that　the　slag　from　biomass-fired　grate　boiler　is　more　suitable　for　direct　use　in　soil　improvement　due　to　the　low　contents　of　hazardous　elements.