The calculations of total energy, band structure, electronic density of states and Mulliken population of LaNi5 have been performed by adopting the method of total energy based on the Density Functional Theory. The augmented plane wave function was selected as the basis set in combination with Ultra-soft Pseudopotential technology. The electronic structures of LaNi5 and LaNisH and the change in the formation of LaNisH were analyzed according to the result of total density of states and partial density of states for different orbits. The metal-hydrogen bonding feature was discussed. The stability of the hydrogen interstitial site and the preferred site occupation of the absorbed hydrogen atoms were preliminarily explored.