In actual operation, the flow rate into the same-layer burners from the large air box is uneven for the swirl opposed-firing boiler, which will significantly affect the burnout characteristics of pulverized-coal. However, there are the research on the burn-out characteristics of single burner in the furnace. Taking a 600 MW front and rear wall swirl opposed boiler as the object, the numerical study and optimization on the burnout characteristics were carried out, and the effects of the air distribution, the swirl intensity and the burner output on burnout characteristics of pulverized coal were also studied. The simulated results show that the carbon content in the fly ash of the lower burner is higher than that of the upper and middle burners, and the carbon content (about 0.1%) in the fly ash of the middle burner is lower than that of the side burners (about 3%), which is consistent with the field measurement results. The incomplete combustion of pulverized-coal from the burner near the side walls is the main source of the carbon content in the fly ash. There is a relatively small impact on the burnout characteristics of the middle burner by appropriately reducing the air ratio of the middle burner and increasing the air ratio of the burners near the side wall, which can effectively improve the burnout characteristics of the burners near the side wall (the carbon content in fly ash reduces from 3% to less than 1.6%). Appropriately increasing the swirling intensity of the burner near the side wall, or properly increasing the output of the middle burner and reducing the combustion output of the burners near the side wall, can significantly reduce the carbon content (less than 2%) in the fly ash of the burners near the side wall and improve the pulverized coal burnout characteristics.