The Primary air can maintain boiler fluidized state, at the same time; it can provide some of the oxygen required by the fuel burning. During operation, the critical fluidization airflow curve under different material thickness shall be made according to the cold-state test before the boiler is started as the adjustment limit of primary air during operating. If the air volume is lower than this value, the material layer fluidization may be bad, and will coke after long time. The secondary air can supplement the air volume required by the combustion of upper part of the hearth of the boiler to make the fuel fully mix with the air and reduce excess air coefficient. The oxygen shall be controlled at 3% to 5% generally to ensure sufficient combustion. When full load is reached, the proportion of primary air and secondary air in the total air volume is associated with coal types. The adjustment of air volume shall be based on the principle that the primary air can ensure the fluidization and adjustment of the bed temperature and the secondary air can adjust the coefficient of excess air and pollutants discharging requirements. Pay attention to that while adjusting the primary air flow and the secondary air flow, it is required to adjust the air-induced amount in order to keep air pressure balance.   (lsh)