Abstract: The performance of the horizontal bias burner directly affects the effect of pulverized coal combustion in the furnace. In order to study the optimal structure of horizontal thick and light burners under 20%~100% different loads, the burners of a 10 MW coal experimental platform were taken as the research object, and numerical simulation of burners with different structures was carried out by using fulent software. The combustion characteristics of the furnace at 9∶1, 8∶2, 7∶3 and 6∶4 were studied numerically. The results show that the load change does not affect the performance indexes of the louver type horizontal thick-dilute burner, such as the thick-dilute air ratio and concentration rate. With the increase of the fifth grade blade Angle, the concentration ratio decreases and the concentration rate increases. Compared with the ratio of blade spacing, the Angle of blade plays a more important role in reducing the ratio of thick to light air and increasing the concentration rate. When the Angle of the fifth grade blade is increased and the ratio of blade spacing is changed at the same time, the wind intensity ratio decreases obviously. As the Angle of the baffle increases, the ratio of thick to light air gradually decreases, but when the Angle increases to 50°, the concentration rate will increase. When the Angle of the fifth stage blade and the Angle of the baffle are both 45°, the concentration ratio is 1.26, the concentration rate is 1.52, and the separation performance is better. The combustion conditions in the furnace are different when the ratio of pulverized coal is different. With the increase of the density ratio, the overall temperature of the furnace also rises, and the combustion in the center of the furnace is basically symmetrical, but when the density ratio continues to increase to 9∶1, the overall temperature of the furnace begins to decline, indicating that the excessively high density ratio is not conducive to the stable combustion of the unit, and the best density ratio is 8∶2. After optimization, the density separation ratio of the burner is close to 8∶2, which verifies the rationality of the burner structure under low load （40%） of the unit.