The adsorption, the diffusion and the dissociation of H2O molecule on α-U(001) surface have been studied using density functional theory (DFT) within generalized gradient approximation (GGA). The calculation results indicate that H2O molecule is preferentially adsorbed on the top site in a flat-lying configuration with the adsorption energy of 0.58 eV. The adsorption interaction is mainly contributed by the overlapping between the 1b1 orbital of H2O and the 6d orbital of the top-layer U atom, along with some weak H2O 3a1-U 6d mixing. The activation energy for H2O diffusion between two adjacent top sites is 0.20~0.23 eV, indicating that the on-surface diffusion is easy for H2O molecule. The OH+H dissociative adsorption is about 1.24~1.39 eV higher in energy than molecular adsorption, together with the dissociation barrier of 0.56~0.62 eV, suggesting that the dissociation of adsorbed H2O into OH and H can occur under the certain heat activation condition