Abstract: Due to the shortcomings of strontium titanate (SrTiO₃) with large band gap and low separation rate of photogenerating carriers, its photoelectrochemical cathodic protection performance is limited. And in order to solve this problem, SrTiO₃ can be modified with the supporting cocatalyst Ti₃C₂. Firstly, SrTiO₃ was prepared by hydrothermal method and Ti₃C₂ was obtained by etching. Then, Ti₃C₂/SrTiO₃ composites were prepared by mechanical mixing. XRD, XPS, SEM, UV-vis DRS, and PL had characterized the phase structure, chemical state, microscopic morphology, and light absorption performance of the samples. Finally, the photoelectrochemical cathodic protection performance of Ti₃C₂/SrTiO₃ composites to 304 stainless steel (304SS) was analyzed. The results show that Ti₃C₂/SrTiO₃ composites are broadened to absorb visible light. Among them, the photogenerated carrier separation rate of the 15%-Ti₃C₂/SrTiO₃ composite with a mass fraction of 15wt% of Ti₃C₂ has a higher separation rate and an optical current density of 2.5 μA·cm⁻². In the 3.5wt% NaCl solution, after the coupling of 304SS to the composite, its photomotive potential drops by 200 mV under light conditions, which can effectively protect 304SS. After four open and closed light cycle tests, the performance of Ti₃C₂/SrTiO₃ composites are stable.