Abstract: Under the consideration of the effect of evaporation of the vaporizer, this paper utilizes the computational fluid dynamics (CFD) software, fluent, to numerically simulate the convection section of an ethylene cracking furnace. Moreover, the modeling of convection chamber and different tube sections are made, respectively, in which the flow of flue gas and oil gas adopts the standard k-ε turbulence model, the two-phase flow in the vaporizer adopts the volume of fluid (VOF) model, and the radiation heat transfer and the multi- components in the convection chamber adopt the discrete ordinates (DO) model and the species transport model, respectively. The simulation results are in agreement with the industrial data. And then, the heat transfer and flow in the convection section are analyzed. It is shown via these results that there exist two recirculation zones at the bottom of the convection chamber and the 90 degree corner of the cross section, which results in the residence time of the high temperature flue gas to increase here and yield a hot spot at the bottom of the mixture heater. This is not conducive to the long period operation of the cracking furnace. The results of the coupled calculation under the consideration of evaporation effect of the vaporizer will be more accurate. The heat absorption of the tubes is influenced by the position of the tubes, and the temperatures of tube skin and the oil gas at outlet in different tubes are different. These simulation results have reference significance for the design and operation optimization of the cracking furnace.