The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shells of both Fe2＋ and Fe3＋ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2＋ and 1.96 for Fe3＋, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2＋ aqueous solution. The corresponding X-ray absorption near edge fine structure （XANES） calculation successfully reproduces all features in the XANES spectra in Fe2＋ and Fe3＋ aqueous solution. A feature that is located at energy 1 eV higher than the white line （WL） in an Fe3＋ aqueous solution may be assigned to the contribution of the charge transfer.
