The present invention provides a gas combustion burner having a mixing space for gas fuel and air. An intermediate burner which has gas suction holes, air suction holes and upper gas discharge holes is disposed among the side burner assembly in a Bunsen burner used for gas boiler. The air-fuel burning rate is improved at the gas discharging holes in order to improve the burning performance. Therefore, the whole length of the flame is reduced, the flame temperature is lowered, thereby the load in same area is reduced and the generating amount of pollutants such as carbon monoxide and nitric oxide can be reduced. |