Abstract: In order to solve the phenomenon of large-area burning of OPCC swirl burner in engineering practice, based on the commercial computational fluid dynamics software FLUENT, carried out the numerical simulation of two flow combustion characteristics on OPCC swirl burner. The control variable method is used to study the thermal combustion characteristics under variable central air, primary air, internal and external secondary air speeds, the results show that: The central wind speed has a negative correlation with the ignition point of pulverized coal. A lower central wind speed is easy to cause burning loss accidents at the burner nozzle, a higher central wind will shorten the axial length of the high-temperature combustion zone, which is not conducive to the full combustion of pulverized coal; Low primary air velocity is also easy to cause burner nozzle burning loss, while high primary air velocity will delay combustion in the furnace and increase the probability of inducing high-temperature corrosion; The probability of inducing high-temperature corrosion will be increased by using the internal secondary air velocity lower than the primary air velocity or too high. The internal secondary air velocity lower than the primary air velocity cannot gather the high-temperature combustion zone together, which is not conducive to the full combustion of pulverized coal. However, the higher internal secondary air velocity leads to the decrease of turbulence in the high-temperature combustion zone, which is also not conducive to the full combustion of pulverized coal; The use of external secondary air velocity lower than the primary air will cause burning loss of burner nozzle, ash slagging on heating area and high-temperature corrosion, which will seriously endanger the safe operation of boiler unit. Too high external secondary air is not conducive to the good formation of central large reflux area, and is easy to induce partial combustion in the furnace and affect the hydrodynamic safety of boiler.