Uranyl　ion　adsorption　on　the　hydroxylated　alpha-quartz　(101)　surface　was　investigated　by　first-principles　density　functional　theory　calculations.　We　explicitly　considered　the　first　hydration　shell　of　the　uranyl　ion　for　short-range　solvent　effects　and　used　the　conductor-like　screening　model　(COSMO)　for　long-range　solvent　effects.　Both　the　adsorption　energies　and　electronic　structures　of　the　adsorption　system　indicated　that　the　bidentate　hydrated　uranyl　species　were　more　stable　than　bidentate　hydroxylated　species,　and　bidentate　adsorption　of　the　uranyl　ion　on　the　bridge　site　of　dia-Os1Os2　was　the　most　stable　adsorption　model　in　the　aqueous　state.　The　large　differences　in　the　electronic　structures　of　the　two　forms　were　mainly　because　of　the　different　degree　of　bonding　between　uranium　and　the　surface　after　adsorption,　which　makes　the　5f　orbital　narrow　and　causes　a　red　shift.　Use　of　halogen　ions　in　the　uranyl　coordination　environment　can　adjust　the　band　gap　of　the　uranyl　adsorption　system.