The ejector of low NOx burner based on the premixed combustion theory was designed in this study. The new designed burner focusing on the flowing and mixing processes of town gas ejector were optimized by CFD approach and validated by experiment. A comprehensive study was conducted to understand the effects of geometrical parameters on the static pressure of air and methane, and the mole fraction uniformity of methane at the outlet of ejector. The distribution chamber was applied to balance the pressure and improve the mixing process of methane and air in front of the fire hole. A distribution orifice plate with seven distribution orifices was introduced at the outlet of ejector to improve the flow organization. It was found that the nozzle exit position NXP = 5 mm and nozzle diameter d > 1.3 mm should be used to improve the flow organization and premixed combustion for the designed ejector. For the new designed burner, the concentration of NO emission is less than 40 ppm when alpha > 1.5, NXP = 5 mm and d > 1.3 mm. (C) 2013 Elsevier Ltd. All rights reserved.