In this paper, a numerical model of the molten salt furnace process was developed, by using computational fluid dynamics (CFD) technique and considering the gas flow, the combustion and the radiation heat transfer. The results demonstrate that the performances of the salt furnace could be improved by optimization using the numerical model. The temperatures along the circumference of the furnace coil and outside shell are quite even, and the deviant combustion phenomenon is not observed. A back-flow formed in the upper part of the furnace chamber enhances the circulation and the mixing of the gas and effectively stabilizes the combustion in the furnace. The behaviors of CO, CO2, NOx, and H2O are presented in terms of the gas flow, temperature distribution and volumetric concentration distribution. It is concluded that the furnace with the constant air flow rate of 15,500 Nm3/h and the guiding vane angle at 48–50 deg is optimized for the combustion effectiveness.