The effect of addition of RE and Ti on the microstructure and corrosion resistance of Zn-2.5Al-3Mg alloy were investigated by XRD, SEM, TEM and XPS. Results reveal that the microstructure of the Zn-2.5Al-3Mg alloy is composed of Zn-rich phase, binary eutectic (Zn-MgZn₂/Mg₂Zn₁₁) and ternary eutectic (Zn/Al/Mg₂Zn₁₁). New phases of (Ce_1?xLa_x)Zn₁₁ and Al₂Ti appear with the addition of RE and Ti elements. Electrochemical impedance spectroscopy indicates that the corrosion resistance of Zn-2.5Al-3Mg-0.1RE-0.2Ti alloy can be significantly improved compared to that of Zn-2.5Al-3Mg alloy. XPS analysis results show that the addition of RE element promotes the formation of Zn₅(CO₃)₂(OH)₆ and MgAl₂O₄ in the corrosion products, while the simultaneous addition of RE and Ti elements promotes the formation of corrosion products Zn₅(CO₃)₂(OH)₆, ZnAl₂O₄ and MgAl₂O₄, and inhibits the formation of loose porous ZnO. Zn₅(CO₃)₂(OH)₆, ZnAl₂O₄ and MgAl₂O₄ attach well to the surface of the sample, which provides a dense protective layer for the alloys, thus improving the corrosion resistance of Zn-2.5Al-3Mg alloy.