Abstract: Using pure magnesium ingot and Mg-30Ce master alloy as raw materials, Mg-Ce alloys with Ce mass fractions of 0.1%, 0.5% and 1% were prepared by melting, and were solution treated at 420℃ for 8 h. The effect of solution treatment on the microstructure and corrosion resistance of alloys with different Ce contents was investigated. The results show that a large amount of Mg-Ce rare earth phase was precipitated at the grain boundaries and in the grains of as-cast Mg-Ce alloys with different Ce contents, and the amount of rare earth phase increased with increasing Ce content. After solution treatment, the rare earth phase was mostly dissolved in the magnesium matrix. The corrosion form of as-cast alloys with different Ce contents was pitting corrosion. The rare earth phase and the magnesium matrix formed a galvanic cell, and the magnesium matrix was protected as a cathode, so the alloy had good corrosion resistance. After solution treatment, the Ce element was dissolved in the magnesium matrix to enlarge the corrosion area, compared with the as-cast state, the self-corrosion current of the alloy increased significantly, the corrosion resistance decreased, and the corrosion form changed to surface corrosion. The higher the Ce content, the worse the corrosion resistance of the alloy.