Abstract: The traditional boiler combustion air flowrate control is based on the concept of air to coal ratio,and the feedforward roughly adjustment is made according to the fuel flowrate,and the fine adjustment is made according to the deviation of the oxygen content in the flue gas.The adjustment of fuel flowrate will affect the control of air flowrate.The development of smart power generation technology needs to innovate the existing basic methods of existing combustion control.The essence of coal-fired generation unit control is load control,that is,the energy conversion stages should be adjusted according to the load demand from the release of chemical energy in fuel combustion to the power generation of turbo-generator. The theoretical air volume required for different kinds of coal in combustion to produce the same amount of heat( corresponding to roughly the same energy level and power output of the unit) was basically unchanged,which was consistent with the conclusions in the relevant authoritative technical works.Therefore,the concept of " air-carbon ratio" was proposed to replace " air-coal ratio",that is,the ratio of a certain mass of air to a certain mass of carbon in complete combustion,which is about 11.5( mass ratio),being roughly constant for different types of coal. The concept of air-heat equivalent is further put forward,which means that the heat released by any kind of coal burning steadily and continuously per kilogram of air in a confined space( furnace) is approximately equal to a constant value of 3.01 MJ/kg air.On this basis,it is proposed that the total air flowrate rate into a boiler should be controlled mainly according to the change of load demand,and the influence of fuel kind changes can be neglected in the total air flowrate control under the same load level.If the efficiency of boiler decreased as the change of coal kind burned in the boiler,more heat would be generated by the fuel in the furnace,and the air flowrate of the boiler should be increased,and vice versa.The new concept of air flowrate control in this paper has been successfully applied into a 300 MW tangentially coal-fired power generation unit from August 2017.The input rate has exceeded 80%,which laid a foundation for the implementation of a new strategy of air-coal decoupling and independent control for boiler combustion.