Abstract: The flame length of aggregate drying pulverized coal burner has a reasonable range of variation due to equipment conditions, fuel properties and working condition parameters, which affects the aggregate drying effect as well as pulverized coal combustion efficiency and pollutant emission characteristics.In this study, the aggregate drying process and thermodynamic requirements were thoroughly analyzed, theoretical analysis and simulation calculations were combined.By studying the mechanism of pulverized coal combustion and the mechanism of pollutant formation, the control model of pulverized coal jet flow, combustion, radiation and other behaviors was constructed accurately and the numerical simulation of combustion behavior was conducted.In addition, the turbulent diffusion and mixing of the internal flow field of the burner affects the length of the flame.Thus, the influencing factors on the flame length of a pulverized coal burner were analyzed comprehensively, then the control law of flame length, pulverized coal combustion efficiency and pollutant emission characteristics were studied.Combined with aggregate drying process requirements, the flame length control rule in pulverized coal combustion was explored in order to improve the efficiency of combustion and reduce the emission of pollutants.The conclusion shows that the primary air preheating temperature, pulverized coal concentration of primary air, primary wind speed and swirling intensity of secondary air all affect the flame length of the aggregate drying pulverized coal burner.The most significant effect on the flame length is the pulverized coal concentration.The higher the pulverized coal concentration, the longer the flame length.The range of flame length is 4.15-5.0 m, with the longest increase of 22%, and the range of maximum flame width is 0.7-1.1 m.The range of flame diameter to length ratio can be extended to 1∶5-1∶9 by adjusting the physical factors reasonably (usually 1∶4-1∶7).Combustion efficiency and emission characteristics of pulverized coal burners are affected by combustion temperature, component concentration and internal flow field state.Under different structural parameters and control conditions, the variation of combustion efficiency and pollutant emission with the flame length are different.Under the premise of meeting the requirement of aggregate drying flame length, the combustion efficiency could be improved and the emission of pollutants could be reduced by reducing the primary air preheating temperature, reducing the pulverized coal concentration, increasing the swirling intensity and increasing the wind speed.