In this paper, the aqueous adiabatic electron affinity (AEA) of Uracil (U) and internal reorganization energy λ i of the self-exchange electron transfer (ET) reaction between Uracil and Uracil anion radical (U − ) in aqueous solution were studied. The effect of the solvation was studied with the recently developed hybrid quantum molecular chemical method, ONIOM. In all calculations, the geometrical optimization for U and U − was performed at B3LYP/6-31++G(d) level. As for the solvent surroundings, the seven water molecules as the first hydration shell were adopted and treated with B3LYP, PM3 and AMBER methods, namely, ONIOM (B3LYP:B3LYP), ONIOM (B3LYP:PM3) and ONIOM (B3LYP:Amber) methods, respectively. The values of AEA for Uracil, predicted by the above three methods, are small positive ones. The geometrical differences between neutral and anion radical molecules of U originate mainly from those of dihedral angles. According to the corresponding dipole moment values, the excess electron in U − should be trapped dominantly by dipole-bound way. The calculated λ i values by ONIOM (B3LYP:B3LYP) and ONIOM (B3LYP:PM3) are close to each other within 0.89%. The λ i value from ONIOM (B3LYP:Amber) is in agreement with the one from SCRF-CPCM very well. Finally, the calculation results of the detailed geometries and molecular interaction mode effect of U and U − and related water molecules in the hydration shell were discussed.