La0.75Mg0.25Ni3.5(TiNi3)0.1 alloys were prepared by induction melting followed by annealing treatment at 1173Kand 1h,2h,5h,12h,respectively. Alloys structure and electrochemical properties have been studied systematically by X-ray diffraction(XRD) with the Rietveld methold , Electron probe micro-analyzer (EPMA)and electrochemical experiments. Alloys structure analyses showed that all of the alloys mainly consisted of complex phases such as LaNi5 phase (CaCu5-type,SG: P6/mmm), (La ,Mg)2Ni7 phase (Ce2Ni7-type, SG: P63/mmc)and (La,Mg)2Ni7 phase(Gd2Co7-type,SG: R-3m). Annealed treatment was benefited to the formation of (La ,Mg)2Ni7 phase. Annealed time was imprtant for the alloys microstructure, for the alloys with annealed for 1 hour,the microstructure between main phase and TiNi3 phase was three-dimensional network,with the annealed time incresed,the TiNi3 phase became reunite. The microstructure of three-dimensional network was useful for the electrochemical cycle stability of alloys electrodes(S100=87%).