Alloying Mg with rare-earth element and nickel is one of the approaches employed to enhance the reaction thermodynamics and kinetics [1].The emphases have been paid the on the interaction among the phases (RE hydride,Mg hydride and Mg2Ni hydride) after the decomposition in the first hydriding process,and the results indicated the RE hydride and Mg2Ni phases can effective catalyze hydrogen sorption reaction and improve the hydrogen sorption kinetics of La-Mg-Ni alloys[2-3].