In the past 10 years, domestic scholars and engineers have carried out a large number of academic research and engineering applications related to coal -fired coupled sludge power generation technology, but most of the research and application are carried outat more than 70% load of the unit, and there are few rele-vant studies on the carbon emission reduction effect of coal-fired coupled sludgepower generation. In order to understand the full range of effects of coal-fired coupled sludge power generation technology on boilers under medium and low load conditions, field engineering tests of coal -fired coupled domestic sludge power generation under 50% loadwere carried out on a 700 MW quadrangle tangential pulverized coal boiler. The effects of coal-fired coupled sludge power generation onboiler thermal efficiency, pollutant emission, dioxin emission, heavy metal content of by-product and CO2 emission were systematicallystudied. The results show that under 50% rated load, the boiler thermal efficiency decreases by 0.52% with 3% sludge and 1.03% with6% sludge, compared with that without sludge. With the increase of sludge ratio, the carbon content of slag also increases correspondingly, which directly leads to the increase of heat loss in physical incomplete combustion. The incineration sludge has no significant effect onthe discharge of dust, SO2, NOx and other conventional pollutants in coal-fired power plants, and the treatment capacity of the environmental protection facilities of the power plant units can fully ensure that the regulated pollutant discharge during the incineration sludge isin line with ultra-low emission standards. The higher the proportion of mixed sludge, the higher the removal rate of dioxins in flue gas purification plant, and the dioxins toxicity equivalent of all operating conditions are lower than 0.01 ng/ m3 stipulated in DB 31/ 1291—2021" Emission Standard of Air Pollutants in coal-fired coupled Sludge Power Plant" . Cr, Cu, Zn in fly ash, Cr, As, Ba, Ni, Zn in slag,and Cu in desulfurized gypsum are relatively sensitive to sludge blending ratio. Considering the use of by-products for soil improvement,the heavy metal content of by-products in power plant under sludge blending condition still meets relevant agricultural standards. According to theoretical calculation, 3% sludge will emit 0.15% more CO2, 6% sludge will emit 0.3% more CO2, the application of coupledsludge power generation technology needs to be optimized in sludge type, sludge pretreatment, combustion load, combustion adjustmentand other aspects, in order to achieve the synergistic effect of pollution reduction and carbon reduction.