The aim of this work is to perform a thermal analysis of the operational conditions of a large-scale roller conveyor furnace in a ceramic factory. The entire furnace was divided into three subzones according to the combustion conditions, and the temperature and gas (CO2, H2O vapor, and O-2) distributions of each subzone were evaluated. The computational fluid dynamics (CFD) approach was employed to simulate the flow, temperature profile, and heat transfer. The realizable k-epsilon model was applied for turbulence simulation of the fluid flow coming from the burners. The discrete ordinates method (DOM) and weighted sum of gray gases (WSGG) model were used for simulation of the radiative heat transfer of the furnace. The high accuracy of the simulation methods was validated with the temperature data of the furnace measured by an infrared thermal camera. From the comparisons between the furnace's operating conditions and the numerical simulations, it was concluded that the simulation methods yielded successful results, and relative deviations of up to 22% were observed in the side wall.