With the theoretical analysis on operating characteristics of a heating-retrofitted unit, the effect of unit heating on the gross coal consumption and adjustable power load is evaluated. Through the quantitative analysis of 135MW and 300MW condensing units in different heating modes, the effect on energy-saving and the power load impacted by heating-retrofitted is calculated. The results can provide valuable reference for the electric power dispatching department to arrange power load reasonably and realize energy-saving generation.