A method for preheating steel scraps using waste heat in a continuous casting process was proposed. Experiment and numerical analysis were carried out to examine the ability of scrap preheating and to determine the factors affecting the rise in scrap temperature. Coupled natural convection-radiation heat transfer was solved by three-dimensional FEM. The distance and the constant a were found to influence the sample's temperature rise greatly. The overall Nusset number can be obtained as Nu(0) = (-0.33alpha(*)D(*0.8) + 7.08)Ra(0.15)t(*-1) - 32.4D(*-0.99)alpha(*-1.98).