A　systematic　study　of　series　of　hydrated　UO2Xn(H2O)(5-n)　(X=F,　Cl,　Br;　n=1　similar　to　4)　and　non-hydrated　UO2Xn　(X=F,　Cl,　Br;　n=1　similar　to　6)　of　halides　on　properties　of　geometries　and　UV-Vis　Spectra　in　aqueous　phase　has　been　carried　out　using　relativistic　density　functional　theory.　Xnm　forms　are　used　to　name　the　series　of　uranyl　halides　(X=F,　Cl,　Br;　n　is　the　number　of　halogen　ligand,　and　m　is　the　number　of　water　molecular　ligand　in　uranyl　complexes).　Solvent　effects　estimated　by　the　conductor-like　screening　model　(COSMO)　use　the　solvent　accessible　surface　(SAS).　Time-dependent　density　functional　theory　includes　spin-orbit　coupling　relativistic　effects　(SO-TD-DFT)　is　used　to　calculate　UV-Vis　absorption　spectra.　The　increase　of　F　ligand　in　structure　elongate　the　U=O　bond　significantly,　however　the　number　of　Cl　and　Br　ligands　make　small　changes　in　bond　U=O.　With　the　increasing　in　number　of　X　ligand　and　water　molecules　participate　in　coordination,　the　binding　energy　of　U　and　X　ligand　can　be　gradually　reduced.　The　calculated　UV-Vis　absorption　spectra　indicate　that　uranyl　fluoride　complexes　does　not　appear　the　characteristic　absorption　peak,　and　uranyl　chloride　and　uranyl　bromide　complexes　have　various　features　in　the　absorption　spectrum.　And　molecular　orbital　analysis　can　well　explain　the　characteristics　of　spectrum.