In this paper, the radiation section of ethylene dichloride (EDC) cracking furnace, considering the chemical reaction, was numerically modelled using computational fluid dynamics (CFD). This study investigated the influence of some parameters such as mass flow rate, the inlet temperature of fluid into the radiation section, and heat flux on the conversion and changes in velocity, pressure, and temperature of the fluid along the coil passes, as well as the outlet stream of the coil. Then, the modelling results were compared with a series of industrial data of an industrial EDC cracking furnace. The results showed that considering the variable heat flux boundary condition is more compatible with the industrial data rather than the constant heat flux boundary condition. Increasing the feed inlet temperature to the furnace, increased the EDC conversion due to the endothermic nature of the thermal cracking reaction. Furthermore, reducing the inlet mass flow rate led to a significant increase in the conversion, temperature, and mass fraction of the products due to an increase in residence time.