In this paper, based on the first-principles density functional theory, the crystal structures, band stuctures and chemical bond properties of high-temperature phase(short for α-LiHB), low-temperature phase(short for β-LiHB) in LiN₂H₃BH₃ and LiNH₂BH₃(short for LiAB) materials for hydrogen storage have been studied. The caculated hydrogen removal energies showed that H_δ+(N₁), connected with Li , played a major role in the intial stage of dehydrogenation and low-temperature phase β-LiHB was easier to desorpt hydrogen than high-temperature phase α-LiHB. Then, HOMO and LUMO caculated by Dmol₃ indicated that dehydrogenation of α-LiHB was through H-N₁…B and H-N₂…B, while β-LiHB and LiAB were only through H-N₁…B. The energy gap of HOMO-LUMO suggested that chemicalSstability of LiAB, α-LiHB and β-LiHBH was: LiAB＞α-LiHB＞β-LiHB. All the researches provided theoretical basis for the synthesis of polyphase LiHB in some way.