Abstract: In the absence and presence of water, the absorption properties of uranium on the (010) surface of goethite (α-FeOOH) were studied by first principle. It is found that the adsorption energy of a water molecular on the (010) surface is at the range from -0.56 eV to -0.85 eV, depending on their initial configurations on the surface. It is also found that in the absence of water, uranium atom might be adsorbed into an octahedral site, or a substitution site, or a bonding bridge site between two oxygen atoms of the (010) surface of goethite. In the presence of water, the water molecular might enhance the absorption ability of uranium atom on the (010) surface of goethite when uranium atom occupies the substitution site and octahedral site. In this case, the adsorption energy of uranium atom on the surface may be reduced by 1.2 eV by water molecular. When uranium atom occupies the bridge site between two oxygen atoms on the surface, the water molecular may either enhance or weaken the adsorption ability of an uranium atom on the (010) surface, and it depends on the initial configuration of water molecular on the surface. But, no matter how, these adsorption processes of water and uranium on the (010) surface of goethite all belong to exothermic reaction. The lattice distortion induced by a uranium atom adsorption on substitution site, octahedral site, and bridge site between two oxygen atoms of the (010) surface of goethite or by a water molecular adsorption on the surface is found to be small, and all the bonding length changes concerned on the surface are less than 0.055 nm. All these cases result from the interaction between U, O, Fe, and H atoms, where partial electrons of the U, Fe, and H atoms transfer into the O atoms.