The bulk amorphous alloy Mg60Ni23.6Y0.5La15.9 was prepared by copper-mold inject casting. Its microstructural transformation and electrochemical properties were investigated. The microstructures of Mg60Ni23.6Y0.5La15.9 amorphous alloy during charge and discharge cycling were characterized by XRD and SEM. The electrochemical performances of the alloy were tested by an automatic charge and discharge apparatus. The results show that the amorphous structure transforms into crystallized one step by step and Mg2NiH4, Mg2Ni and Mg(OH)2 phases are formed gradually during the process of hydrogenation and dehydrogenation. Furthermore, the result of electrochemical characteristics testing shows that the change process of discharge capacity for Mg60Ni23.6Y0.5La15.9 amorphous alloy can be divided into four stages and the highest discharge capacity reaches 410.5 mAh/g. It is found that the amorphous structure may be a critical factor to obtain the maximum discharge capacity.