The influence of refining flux composition, refining time, refining temperature, and addition amount on the microstructure and mechanical properties of Mg-9Li-3Al-1Zn alloy was investigated with orthogonal experimental design. The flux purification process for Mg-Li alloys was optimized and the most effective ternary flux composition was identified. Results indicate that flux purification significantly mitigates Li loss during smelting by forming a protective surface layer that reduces Li oxidation and evaporation. The optimal flux composition is LiCl？LiF？CaF₂ in a 3？1？2 mass ratio, with a flux addition of 3%, refining temperature of 720 °C, and holding time of 10 min. The elongation of alloy improves to 16.2% after refinement, while the enhancement in strength remains marginal.