Pb-Sn-X alloys (X: additives) are interesting materials as grid of lead acid battery with corrosion-resistance. In this study, Pb-Sn alloys of 0-2.0mass% Sn were prepared by casting, and then the corrosion tests with electrify/immersion cycling were carried out in 4.50kmol/m3 H2SO4 at 348K for 604.8ks. The test resulted in the formation of a peculiar corrosion scale on the electrode surface and black corrosion powders suspended in the electrolyte solution. The mass change of the specimen electrode during the corrosion test, which was caused by formation of the scale composed of PbO2 and PbSO4 and its peeling away, increased with the increasing Sn content ranging from 0 to 1.0mass%. On the other hand, the amount of the corrosion powders suspended in the electrolyte decreased with the increasing Sn content. Consequently, the Pb-Sn alloy of about 2.0mass% Sn had good corrosion-resistance to suppress both the mass change of the sample electrode and the amount of the corrosion powders. Moreover, the corrosion data suggest that not only the crystal structure but also the current efficiency of oxygen generation influenced the formation rate of the corrosion scale. That is, the increasing of Sn content caused a remarkable decrease in the current efficiency of oxygen generation and activated the production of PbO2, PbSO4 and the like. The coarsening of the crystal grain was also effective in suppressing the intergranular corrosion. Therefore, the formation rate of the corrosion scale was synthetically determined by both effects of the grain size and the current efficiency of oxygen generation. In addition, the oxygen generation, which accelerates the peeling away of the corrosion scale, was related to the formation of the powders suspended in the electrolyte.