Magnesium borohydride Mg(BH4)2,having gravimetric and volumetric hydrogen densities of 14.9 wt.% and 112g/L,respectively,is considered as one of the most promising materials for hydrogen storage.Extensive investigations have been paid on this complex hydride in the past few years.We summarized research progresses on the synthesis,crystal structure and hydrogen storage performance of Mg(BH4)2 in this paper.Pending issues,such as kinetic barrier and reversibility of hydrogen storage in Mg(BH4)2,were discussed,and further development of this storage material was suggested.