Effects of Ga and Al additions on the corrosion resistance of Sn-9Zn lead free solder in 3.5% NaCl solution were researched by erosion mass loss evaluation. Effects of the additions on high-temperature oxidation resistance of the solder were investigated by TGA and AES. Results indicate that the corrosion resistance of Sn-Zn solders is improved by addition of Ga, for the corrosion products exhibit better adhesiveness on the solder surface after adding Ga; however, with Al addition, the corrosion resistance deteriorates for the selective erosion of Al and Zn. The TGA results show that the high-temperature oxidation resistance of Sn-9Zn solder is observably improved by adding Ga or Al; the AES analysis shows that Ga could form a protective skin on the solder surface, while Al can form a dense protective oxidation layer, both of which can hinder diffusion of the oxygen to the inner.