Abstract: High grade offshore wind turbine steel with yield strength of 460 MPa was successfully R&D based on ultra fast thermo mechanical control process (TMCP), and based on the principle of low carbon content, low carbon equivalent, micro alloying in composition design and high heat input in welding. The chemical composition design and trial production process of the developed two kinds of steel were described, and their comprehensive mechanical properties were analyzed. The results show that the two developed steels have the characteristics of short production cycle, high strength, good toughness, good lamellar tear resistance, good fatigue resistance, excellent crack arrest performance and can be welded with high heat input, which is in line with the development direction of offshore wind turbine steel.