Abstract: The Mg-3Sn-2Al-1Zn-5Li alloy was heat treated in different ways. The corrosion electrochemical behavior of the heat-treated alloy by different ways was studied by electrochemical testing in 3.5% NaCl solution. The corrosion morphology and the composition of corrosion products were analyzed by scanning electron microscopy, energy spectrum and X-ray diffraction. The results show that the corrosion resistance of the alloy was improved after solution and aging treatment, and the solution-treated Mg-3Sn-2Al-1Zn-5Li alloy had the best corrosion resistance. The corrosion characteristic of the alloy was filiform corrosion, and the main corrosion product was Mg(OH)₂.