Abstract: In view of the deviation of traditional statistical methods in energy saving calculation of cogeneration units, a steam regression calculation method was proposed. The unit was regressed to the pure condensation operation mode to obtain the power and heat consumption of power generation while keeping the intake steam flow, pressure and temperature of the turbine unchanged, and based on this, the energy saving of cogeneration units was calculated. Through calculation and analysis, the algorithm took full account of the influence of cylingder efficiency and steam parameters on the overall power generation heat consumption rate of the unit, so that the calculated energy-saving amount was closer to reality.