The invention provides an online rolling and hot-forming process of a heat-state plate/strip. The online rolling and hot-forming process of the heat-state plate/strip is used for hot-bending and forming a heat-state steel plate or strip steel, so that the heat-state steel plate or the strip steel becomes profile steel with a specified space through a longitudinal cutting process or a hot bending process. The heat-state steel plate or the strip steel is firstly longitudinally cut and then hot-bent, firstly hot-bent and then longitudinally cut or longitudinal cut and hot-bent at the same time; during the longitudinal cutting process, the steel plate or the strip steel is longitudinally cut and slit; and during the hot bending process, the steel plate or the strip steel is continuously hot-bent and formed through a deformation compression roller group. According to the process, the heat-state plate/strip can be directly rolled and bent to form a specific profile steel cross section, and is longitudinally split into long-strip profile steel or a long-strip steel plate; and the long-strip profile steel can be directly used and can be further conveyed to a steel structure processing procedure so as to be welded into the profile steel. By adopting the new production process, the cutting and side processing procedures required for processing the steel plate into the profile steel can be omitted, and the required welding process is reduced or eliminated. The production cost is reduced, and the production efficiency is improved.