Abstract: After deformed and annealed, 70Cu-30Ni alloy with irrecrystallization or incomplete recrystallization mainly consisting of deformed grains displayed unstable E.(corrosion potential) and low Rp (polarization resistance) in 3.5%NaCl, and corrosion product film contained a lot of seawater species in the outer layer and denickelified in the inner layer immersed in seawater for 3 and 6 months, and intergranular corrosion occurred in the matrix. With the increase of deformation and annealing temperature, the anodic oxide film formed by polarization in artificial seawater was increasingly stable. The recrystallized alloy was stable in Ec and high in Rp and its corrosion product film formed in seawater was uniform and rich in Ni.