The corrosion behavior of Cu-4wt.%Ti alloy in solid solution in simulated polluted seawater (3.5wt.% NaCl solution containing S2-) was studied by immersion test and electrochemical test.Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to test and analyze the corrosion products on the surface of copper titanium alloy.The results show that the Cl- causes pitting corrosion of Cu-Ti alloy in solution, and the pitting pits with uniform distribution are smaller in size. When the concentration of S2- in NaCl solution is 60ppm, the pitting pits are connected with each other on the surface of the alloy, showing uniform corrosion morphology.There is competitive adsorption between S2- and Cl- on the corrosion of Cu-Ti alloy, and S2- Corrosion of copper-titanium alloy is severe due to its strong adsorption.In NaCl solution containing S2-, the corrosion products are mainly CuS, Cu2S, Cu2O and Cu2(OH)3Cl.When S2- concentration is high, the concentration of OH- in the solution will increase, which will increase the thickness and density of the corrosion product film. Therefore, when S2- concentration reaches 100ppm, passivation can occur to the Cu-Ti alloy to slow down the corrosion. Key words: Cu-Ti alloy; S2- pollution; Simulated sea water; Corrosion; Competitive adsorption