A method comprises sorting and removing impurities from magnesium alloy waste material, and cleaning and drying said material, the cleaning being high-pressure rinsing, pickling, and water washing, performed in sequence. The method employs high-pressure rinsing during the pretreatment of magnesium alloy waste material; the cleaning effectiveness is excellent, the effectiveness of the removal of impurities from the surface of the magnesium alloy waste material is much better than in conventional processes, and the amount of clean waste material can exceed 90% of the total amount of processed waste material; the clean magnesium alloy waste material obtained from the pretreatment method may be used as the entire raw materials for casting national-standard alloy ingots, the addition of costly high-purity magnesium is unnecessary, and the amount of alloy raw material that must be added is significantly reduced; during processing, little waste material is lost, costs are low, and efficiency is high.