In　order　to　investigate　the　formation　and　transformation　of　ash　species　at　the　different　stages　of　high-alkali　fuel　conversion,　the　ashes　of　wheat　straw　and　Zijin　coal　produced　by　different　ashing　methods　were　studied　in　this　paper.　The　initial　state　of　mineral　in　the　raw　fuel　could　be　kept　well　due　to　the　low　temperature　(150∼200)　of　the　plasma　ashing　method.　The　traditional　ashing　method　with　several　temperatures　(575,　815,　and　1000)　was　employed　to　study　the　formation　and　transformation　of　ash　species.　The　results　show　that　the　potassium　content　in　wheat　straw　ash　and　the　sodium　content　in　Zijing　coal　ash　decrease　roughly　with　the　increasing　ashing　temperature.　The　plasma　ash　sample　of　wheat　straw　contains　KClO4,　the　decomposition　of　which　partly　causes　the　weight　loss　of　this　sample.　The　Na-bearing　minerals　in　Zijin　coal　transform　into　NaAlSiO4　and　other　minerals　at　high　temperature,　and　the　Fe-bearing　minerals　also　go　through　a　variety　of　reactions　like　decomposition　and　oxidation.　The　ferrous　iron　in　wheat　straw　and　Zijin　coal　tends　to　be　oxidized　as　ferric　iron　when　the　ashing　temperature　gets　higher.　©　2022,　Science　Press.　All　right　reserved.