Abstract: The utilization of flue gas waste heat is an important means to reduce the energy consumption. Combined with the actual situation of a 1000 MW new project, two feasible schemes for the deep utilization of waste heat are proposed, namely, air preheater bypass + two-stage flue gas cooler (scheme 1) and air preheater bypass + hot primary air temperature control device + two-stage flue gas cooler (scheme 2). In order to objectively evaluate the energy-saving effect of different schemes, the calculation model of the thermal characteristics of the rotary air preheater was established by using the finite difference method, and the effects of the air preheater bypass flue gas share and the change of inlet air temperature on the boiler efficiency were studied. Based on Ebsilon, a calculation model of thermal characteristics of steam turbine was established, and the effects of different heat input modes and steam extraction volume changes on the heat loss rate of steam turbine were studied. Through further research, it is concluded that the share of flue gas bypass and the inlet air temperature of the air preheater increase, the coal consumption of unit 1 decreases monotonically, and the coal consumption reduction value of unit 2 increases first and then decreases. All things considered, scheme 2 is recommended, corresponding to the best bypass flue gas share of 12%, and the lowest coal consumption reduction value is 3.04 g/kWh.