This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode(Mo electrode) in a molten KCl-LiCl-AlCl3-MgCl2-KF system.It aims at preparation Mg-Li-Al metal alloy directly under an optimal electrolytic parameters.Main factors which affect current efficiency are investigated.We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments,and gained a good electrolytic process.The result of calculation shows that co-electrodeposition Mg,Li and Al occurs at the cathode current density higher than 9 A/cm2 and electrolytic voltage between 6 to 9 V.And at the optimal parameters,12-13 A/cm2,620-640 ℃,the highest current effciency reaches as high as 86%.Lithium combined with magnesium forms Li0.92Mg4.08 and Li3Mg7,and aluminum mainly exists in a form of Mg0.58Al0.42,distributing in the alpha phases and beta phases. This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode (Mo electrode) in a molten KCl-LiCl-AlCl3-MgCl2-KF system .It aims at preparing Mg-Li-Al metal alloy directly under an optimal electrolytic parameters. Main factors which affect current efficiency are investigated. We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments, and gained a good electrolytic process. The result of calculating that co-electrodeposition Mg, Li and Al occurs at the cathode current density higher than 9 A / cm2 and the electrolytic voltage between 6 and 9 V. At the optimum parameters, 12-13 A / cm2, 620-640 ° C., the highest current effciency reaches as high as 86%. Lithium combined with magnesium forms Li0.92Mg4.08 and Li3Mg7, and aluminum mainly exists in a form of Mg0.58Al0.42, distributed in the alpha phases and beta phases.