Abstract: Marine ranch equipment had demands for low cost, lightweight, and high strength. A high-strength marine ranch steel with a yield strength of not less than 420 MPa was developed through optimized composition design and controlled rolling and cooling process regulation. The results show that after the combination of micro-alloying and controlled rolling and controlled cooling process, the microstructure of the steel was a complex phase structure dominated by fine-grained bainite, and the strength and toughness were improved. The yield strength of this steel reached 440-500 MPa, the tensile strength was not less than 540 MPa, the elongation was not less than 20%, the impact absorption energy at -60 ℃ was not less than 180 J, and it had excellent crack resistance and welding performance, which could meet the lightweight and high-strength requirements of marine pastures.