A　systematic　study　of　series　of　non-hydrated　and　hydrated　Cn/m　uranyl　carbonate　complexes　(n　is　number　of　carbonate　ligands,　and　m　is　number　of　water　molecules)　in　the　aqueous　phase　was　carried　out　using　relativistic　density　functional　theory.　The　conductor-like　screening　model　was　used　to　calculate　solvent　effects.　The　zeroth-order　regular　approximation　was　used　to　account　for　scalar　relativistic　effects　and　spin-orbit　coupling　relativistic　effects.　Time-dependent　density　functional　theory　with　the　inclusion　of　spin-orbit　coupling　relativistic　effects　was　used　to　calculate　electronic　transitions　using　the　statistically　averaged　orbital　potentials.　The　results　indicate　that　carbonate　ligands　play　an　important　role　in　the　geometric　and　electronic　transition　properties　of　the　complex.　The　stability　of　the　C3/0　carbonate　complex　in　the　aqueous　phase　may　be　attributed　to　the　involvement　of　5f　components　in　the　highest　occupied　bonding　orbital.　The　addition　of　carbonate　ligands　caused　a　blue　shift　in　the　maximum　wavelength　and　high　intensity　absorptions　in　the　near　visible　region.　©　Editorial　office　of　Acta　Physico-Chimica　Sinica.