Abstract: Nitrogen oxides (NO_x) is one of the main air pollutants that cause photochemical smog and ozone layer destruction. With the increasingly strict emission requirements of pollutants, more and more low NO_x combustion technologies are used in industrial combustion equipment. Based on the principle of partial premixing and internal flue recirculation technology to reduce NO_x emission, an air-staged partial premixing low NO_x swirl burner was developed. The effects of air supply flow rate and classification scheme on flame characteristics and emission performance are studied through experiments and numerical simulation. The results show that the air-staged partial premixed low NO_x swirl burner complied with low nitrogen emission requirement. The combustion flow field consists of two pairs of recirculation zones, the short blue flame is maintained in the head area of the combustion chamber, which inhibits the generation of thermal NO_x. It is found that the flame characteristics and NO_x emission are greatly affected by the fuel premixing and internal flue gas recirculation. With the increase of the tertiary air, the effect of gas recirculation in the combustion chamber is enhanced, the scope of the central recirculation zone is gradually increased, the flame length is shortened, and the temperature and NO_x emission is reduced. Under the condition of 0.71 global equivalent ratio, NO_x emission is about 55 mg/m³(3.5%O₂). The pre-mixing of primary/secondary air and fuel has great influence on combustion stability and emission performance. When the proportion of secondary air in the secondary and tertiary air supply increases, the premixing effect is enhanced, and the combustion stability decreases with the reduction of NO_x emission. When the proportion of secondary air is 65%, the NO_x emission in the combustion process is reduced by about 27% compared with 41%. Under the condition of sufficient primary/secondary air supply and global equivalent ratio of 0.61, the NO_x emission can be as low as 21 mg/m³(3.5%O₂).