The heating process of slabs in the furnace is closely related to quality, productivity, and energy consumption of slabs, during which temperature distribution of slabs plays an indispensable role. Thus, it is particularly important to grasp the factors affecting temperature field of slabs and formulate a reasonable heating style. Since there is a lot of gas such as O2, CO2, and H2O in the furnace during production, oxidation of slabs is inevitable under high-temperature condition. This paper studies the temperature variation of dynamic slabs oxidized during heating process, which provides a reference for guiding the heating process. In accordance with general principles of first developing a model and then simulating, temperature field of three-dimensional dynamic slabs oxidized in walking-beam reheating furnaces are explored. As a result, compared with slabs without oxide layer, those with 2mm oxide layer are worse quality with lower mean temperature of 10.06 square and higher maximum temperature difference of 6.78 square, respectively. Then, for qualified products, the method of lengthening soaking time is adopted to improve the temperature distribution of slabs. The mounting heating time for 1000s in the soak zone is the vintage choice through comparison of several simulation results.