In this study, TC4-xO alloys of 0.10O, 0.15O, 0.25O and 0.35O were prepared by the addition of TiO₂ powder during the melting process. The microstructure and phase composition of the TC4-xO alloys were analyzed using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and X-ray Diffraction. The mechanical properties of the alloys were tested with micro-hardness equipment and electronic universal testing machines. Additionally, the corrosion performance of the alloys was evaluated in simulated seawater and polluted seawater solutions. The results are as follows: All four TC4-xO alloys exhibited a mesh α+β dual-phase microstructure. X-ray diffraction patterns indicate that there are no peaks corresponding to TiO₂ or TiO in the alloy. The oxygen atoms occupy the octahedral interstitial positions of α-Ti, resulting in lattice distortions within the TC4-xO alloy and causing a shift of the α-Ti peaks associated with the c-axis in the low-angle direction. As the oxygen content in the alloy increased, both hardness and strength rose linearly, while plasticity decreased significantly. In the simulated seawater solution, the annual corrosion rate and impedance values of the TC4-xO alloys showed minimal change. In the simulated polluted seawater solution, as the oxygen content increases, the annual corrosion rate and impedance values of the TC4-xO alloy initially decrease and then increase. Notably, the annual corrosion rate of the 0.25O alloy is the lowest, measuring only 2.17 μm/a. All four TC4-xO alloys exhibited breakdown potentials of +0.79 V, and sulfur was detected in the erosion pits. During the corrosion process, S_2- ^{and Cl_-} ions collaborated to disrupt the stability of the TC4-xO alloy surface, which was compromised by a dense oxidation film. This led to micro-battery corrosion, and the corrosion products generated from the reaction of exposed titanium-based materials contributed to further erosion. The findings of this study can guide the optimization of performance for the development of large-sized titanium alloy castings.