Starting from two precursors LaNi5 and LaMgNi4, four alloys with different phase structures were prepared by powder sintering technique. The results suggest that LaNi5 phase can consecutively react with LaMgNi4 phase generating (La,Mg)Ni-3 and (La,Mg)(2)Ni-7 phases, and the mole ratio of precursors LaNi5/LaMgNi4 (x) affects the phase structures of alloys significantly. XRD and Rietveld refinement results demonstrate that the alloys mainly consist of (La,Mg)Ni-3 and (La,Mg)(2)Ni-7 phases (x = 0.28 and 0.59) or (La,Mg)(2)Ni-7 and LaNi5 phases (x = 0.87 and 1.47). When x increases from 0.28 to 0.59, the main phase becomes (La,Mg)(2)Ni-7 phase with Ce2Ni7- and Gd2Co7-type from PuNi3-type (La,Mg)Ni-3 phase. As x rises from 0.59 to 0.87, the secondary phase (La,Mg)Ni-3 disappears with CaCu5-type LaNi5 phase emerging. When x grows from 0.87 to 1.47, the content of LaNi5 phase increases from 17.88 to 60.72 wt.% with (La,Mg)(2)Ni-7 phase content declining. The alloy with (La,Mg)(2)Ni-7 as the main phase and (La,Mg)Ni-3 as the secondary phase is conducive to cyclic stability and the alloy with (La,Mg)(2)Ni-7 as the main phase and LaNi5 as the secondary phase is beneficial to the high-rate dischargeability. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.