Abstract: Energy conservation and efficiency improvement under the dual carbon background is the first choice for coal-fired power plants to reduce carbon. The energy efficiency parameters of dry electrostatic precipitator（ESP）, wet electrostatic precipitator（WESP）, auxiliary equipment and dust removal technology route before and after ultra-low emission transformation were analyzed and evaluated, which could excavate their energy saving and carbon reduction space. Before the transformation of ultralow emission, the annual CO₂ emissions corresponding to the high voltage power consumption of 300 MW, 600 MW and 1000 MW units supporting dry ESP are about 6 000 t, 9 000 t and 14 000 t respectively. In addition, the better the performance of ESP, the higher the corresponding energy consumption and CO₂ emission. After the ultra-low emission transformation, the annual CO₂ emission corresponding to the high-voltage power supply power consumption of the 1000MW unit supporting the ESP is about 18 000 t, which increases by about 20% compared with that before the transformation, but could be reduced by about 60% through the energy saving optimization. The annual CO₂ emissions corresponding to the high-voltage power supply power consumption of the 300 MW, 600 MW and 1000 MW units supporting the WESP are about 2 000 t, 2500 t and 3400 t,respectively. The low temperature economizer of 630 MW unit could reduce the annual CO₂ emission by about 19000 t,and the phase change condenser of 280 t/h furnace could reduce the annual CO₂ emission by about 8 000 t. Compared with the WESP removal technology route, the flue gas cooperative treatment technology route of 660 MW unit with low-low temperature ESP removal technology as the core could reduce the annual CO₂ emission by about 3 000 t. This paper could provide technical ideas for the carbon emission reduction of subsequent coal-fired power plants.