Preparation method of magnesium alloy

The invention discloses a preparation method of a magnesium alloy, and relates to a magnesium alloy with aluminum as a secondary component. The preparation method comprises the steps of weighing commercial AM50 magnesium ingots, pure SiO2 and a commercially available magnesium-cerium lanthanum intermediate alloy according to the mass percents of the component elements of the prepared magnesium alloy; preparing and refining a magnesium alloy solution after the commercial AM50 magnesium ingots and the pure SiO2 raw material are subjected to pretreatment; finally pouring to prepare a magnesium alloy blank, wherein component elements of the prepared magnesium alloy according to the mass percent comprise 4.4-5.4% of Al, 0.24-0.60% of Mn, 0.5-3% of Si, 1-3% of Ce, 1-3% of La, not greater than 0.22% of impurity element Zn, not greater than 0.01% of impurity element Cu, not greater than 0.005% of impurity element Fe, not greater than 0.002% of impurity element and the balance of Mg, and the sum ...