Abstract: Longitudinal profiled (LP) steel plates can optimize material distribution according to bearing requirements and serve as essential materials for the lightweight design of heavy equipment. Quenched and tempered heat treatment is a critical technical route for LP steel plates to achieve strength grades above 400 MPa in future engineering applications. Aiming at the technical problems of gravity deformation and composition adaptation encountered during the heat treatment of 590 MPa grade high-strength marine LP steel plates, this study carried out systematic research including numerical simulation, theoretical calculation and industrial trial production. Through Deform finite element simulation, the gravity deformation law of LP steel plates at a high temperature of 910 ℃ was revealed, the coupling influence mechanism of wedge length and base thickness on deformation was clarified, and the process and dimension windows for controllable deformation were determined. On this basis, combined with material hardenability analysis and Thermo-Calc thermodynamic calculation, the effects of alloy design and copper precipitation behavior on the property matching of thick and thin specifications were analyzed, and the Mn-Ni-Mo-Cu alloy system was optimized. The results show that the deformation degree of LP steel plates increases with the extension of wedge segment length and the reduction of base thickness. When the base thickness is 50 mm, favorable shape stability can be maintained even with a wedge length of 1.5 m. The optimized composition design realizes the uniform grain size control (grain grade of 10.0-10.5) of LP steel plates within the thickness range of 27-35 mm, and the microstructure is dominated by tempered lath martensite and bainite. The industrially trial-produced steel plates possess a yield strength of no less than 650 MPa and a tensile strength of no less than 715 MPa. The Charpy impact energy exceeds 200 J at both -40 ℃ and -84 ℃, with excellent mechanical property uniformity between thick and thin ends. This study realizes the first industrial production of 590 MPa grade heat-treated LP steel plates, providing a theoretical basis and technical support for the engineering application of high-performance LP steel plates.