Abstract: The heat recovery of utility boiler flue gas,used to heat condensed water in the feed water system,can squeeze out proportion of the extraction to return the turbine to continue expansion of acting work.It partly improves unit efficiency and reduces plant coal consumption.Based on the selected working conditions of typical ultra-supercritical units and combined with engineering constraints,this paper carries out a variety of typical integrated excogitations of heating condensed water by utilization of flue gas heat recovery.Both equivalent enthalpy drop method and conventional thermal balance method are used for thermodynamic comparison and analysis.The research shows that computed results of the two methods are very close,which can check each other under engineering computation.On condition that low temperature economizer meets the constraints,it will have better energy conservation effects when high-grade steam extraction is replaced.Simultaneously,reasonable series-parallel connection methods may achieve much better thermal and comprehensive performance.