In this paper, the density functional theory has been used to perform a comparative theoretical study of water monomer, dimer, trimer, and bilayer adsorptions on the Be（0001） surface. In our calculations, the adsorbed water molecules are energetically favoured adsorbed on the atop sites, and the dimer adsorption is found to be the most stable with a peak adsorption energy of - 437 meV. Further analyses have revealed that the essential bonding interaction between the water monomer and the metal substrate is the hybridization of the water 3al-like molecular orbital with the （s, P2） orbitals of the surface beryllium atoms. While in the case of the water dimer adsorption, the lbz-like orbital of the H2O molecule plays a dominant role.
