At room temperature,crystalline Mg-based alloys,including Mg2Ni,MgNi,REMg12 and La2Mg17,have been proved with weak electrochemical hydrogen storage performances.For improving their electrochemical property,the Mg is partially substituted by Ce in Mg-Ni-based alloys and the surface modification treatment is performed by mechanical coating Ni.Mechanical milling is utilized to synthesize the amorphous and nanocrystalline Mg1-xCexNi0.9Al0.1 (x =0,0.02,0.04,0.06,0.08) + 50 wt％Ni hydrogen storage alloys.The effects made by Ce substitution and mechanical milling on the electrochemical hydrogen storage property and structure have been analyzed.It shows that the as-milled alloys electrochemically absorb and desorb hydrogen well at room temperature.The as-milled alloys,without any activation,can reach their maximal discharge capacities during first cycling.The maximal value of the 30-h-milled alloy depending on Ce content is 578.4 mAh/g,while that of the x =0.08 alloy always grows when prolonging milling duration.The maximal discharge capacity augments from 337.4 to 521.2 mAh/g when milling duration grows from 5 to 30 h.The cycle stability grows with increasing Ce content and milling duration.Concretely,the S100 value augments from 55 to 82％ for the alloy milled for 30 h with Ce content rising from 0 to 0.08 and from 66 to 82％ when milling the x =0.08 alloy mechanically from 5 to 30 h.The alloys\' electrochemical dynamics parameters were measured as well which have maximum values depending on Ce content and keep growing up with milling duration extending.