Abstract The properties of BaTiO 3 and the electronic structure of H 2 O adsorption on BaTiO 3 were investigated by using first principle calculations based on density functional theory. The calculated results show that the orbital hybridization between Ti and O is stronger than that between Ba and O. With the increase of energy, reflex points in the form of random fluctuation and the anisotropy of crystal clear. Enthalpy and heat capacity varies with temperature rise, while free energy fall. H bonds are formed between the hydrogen of water and the surface oxygen of BaTiO 3 and between the hydrogen of hydroxyl and the surface oxygen of BaTiO 3 . The adsorption process of BaTiO 3 adsorbing H 2 O is a physical process and Δ H < 0, Δ S < 0.