Large-scale high backpressure cogeneration units can make full use of the waste heat of the spent steam to reduce the unit's cold-end losses, improve the fiel utilization rate, and heating efficiency, the energy saving effect is remarkable. The 2×350MW cogeneration unit of a power plant is modeled as an example. The boundary conditions of the heat network are calculated according to the ambient temperature, and the thermal economy and exergy efficiency of the condensing unit and the high backpressure unit are analyzed during the heating period, to obtain the advantages of the high backpressure unit during the heating period. In turn, the study presents the high backpressure unit extracts steam distribution method is adjusted to optimize the operation strategy during the heating period. The results indicate that: after adopting high back pressure operation during the heating period, the average power generation increased by 24.5MW compared to the condensing unit, The average reduction in coal consumption for power generation is 97.5g•(kW•h)-1, exergy efficiency increased by an average of 9.4%, exergy efficiency of the unit's heating network has increased by an average of 19.2%. After the unit adopts optimized allocation of extraction load, the average coal consumption for power generation is reduced by 0.69 g•(kW•h)-1on the basis of high back pressure heating operation. The average efficiency improvement of steam-water exergic is 0.44%, while the efficiency average improvement of heating networks is 0.6%, with a maximum increase of 1.4MW of exergy energy.