Abstract: The geometric structures and electronic property of the beryllium clusters Be_n(n=2～6) were investigated by using GGA PW91/DNP based on density functional theory. Total energy, average binding energy, vibrational frequencies, the highest occupied and lowest unoccupied molecular orbitals energy, energy gaps, vertical ionization potential and electron affinities were all calculated. After hydrogen molecule was absorbed at the top, bridge and hollow site, it was calculated in terms of geometric optimization, adsorption energy, and Mulliken atomic population analysis. The results show that the stability of clusters is reinforced gradually due to increasing beryllium atoms. Adsorption energy is in the range of 0.006 198 2-0.008 972 2 a.u. After H₂ is adsorbed on the beryllium clusters, the extent of hybridization strengthens with increasing beryllium atoms. The more electric transferred charge of adsorption site is, the stronger adsorption force is.