Abstract: For improving the combustion effect of the large-scale steady combustion fogger, reducing the emission of harmful gas of CO, hydroxide and so on, and decreasing the precipitation of the carbon particle, a method of simulating the combustion process and the distribution of the exhausted gases in a combustor was studied to improve the design of the large-scale steady combustion fogger. In the simulation, first, the combustor was simplified to a two-dimensional symmetrical model and the geometric shape of the combustor was established to generate the grid with the Gambit software. Then the combustion and generating process was simulated and calculated with the prePDF program. The mol mass fraction of the combusted product was calculated in the turbulence model and non-premix model of FLUENT. Finally, the chemical component of the exhausted gas was tested by the exhausted gas detector. The research is beneficial for the analysis of the ratio of fuel to air, the product of the exhausted gases, the heat mixture in the exhausted tube and the generation of optimum droplet.