In the present study, we used density functional theory with B3LYP/6-311g++(d, p) method to calculate the structures, frequencies and energies of (LiBH4)n, n=1~12 clusters which has been known as a candidate hydrogen storage materials. We found that each cluster has several isomers. In order to enhance the hydrogen storage capacity of (LiBH4)n clusters, we added excess electrons to(LiBH4)n clusters. Our calculations show that the hydrogen storage capacity as well as the weight percent is improved with the existence of excess electrons. In addition, we also analyzed the distribution of the charge.