Aluminum-magnesium alloys were prepared from magnesium oxide by molten salt electrolysis method. MgF2-BaF2-LiF was taken as electrolysis.Since the density of MgF2-BaF2-LiF was high than aluminum liquid, upload cathode of aluminum liquid was used in the tests. Current efficiency during melting was more than 80%, and the maximum was up to 87.7%. Some amount of magnesium oxide flowed into electrolytic cell. The content of Mg in alloys increased gradually and up to maximum of 18.6%(w) with electrolyzing time. The experiment results revealed that the addition of KCl improved the physical-chemical property of the melten salt.