Abstract: In order to improve the hydrogen storage property of LiBH₄, 2LiBH₄/LiAlH₄/0.5CaC₂ composite was prepared with ball-milling method. The de-rehydrogenation properties and reaction mechanism were investigated with X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and pressure-composite-temperature testing apparatus(PCT). The results show that dehydrogenation of the 2LiBH₄/LiAlH₄/0.5CaC₂ composite accomplishes at approximately 440℃, with about 6.2% (mass fraction) of hydrogen totally desorbed. In the process of hydrogen desorption, CaC₂ is directly involved in the reaction to cause the destabilization of the reaction, thus improving the dehydrogenation property. After rehydrogenation at 450℃ and 9 MPa for 12 h, 5.4% (mass fraction) of hydrogen can be absorbed. The reversible hydrogen storage property is improved obviously with respect to pristine LiBH₄.