Abstract: Current cogeneration energy consumption evaluation methods simply allocate the energy saving benefits to power generation or heating. The difference of the quality of electric and heat cannot be reflected. To make up deficiencies of current evaluation methods, we divide the steam into condensing steam and heating steam. The cycle exergy loss is allocated to power generation and heating according to the source. Through exergy analysis, we establish the unified expression of cogeneration product and cogeneration energy consumption. The energy quality coefficient is introduced to simplify the calculation process of energy consumption. The cogeneration specific fuel consumption analyzing model based on exergy analysis is expanded to describe the time and spatial distribution of energy consumption. The rationality of new method is verified by example. The result shows that the exergy is released to supply water and the cycle exergy loss of heating steam constitute heat load. Cogeneration realizes energy saving in power generation and heating by recovering cold source exergy and matching the quality and quantity of energy. The unified energy consumption calculation method can reflect the quality of electric and heat and reveal the way of exerting energy saving potential.