Biomass co-firing in coal-fired power plants has the advantages of low conversion cost,flexible peak shaving,and safe operation. It is an effective way for the power plant to reduce CO2 emissions and increase the proportion of renewable energy in power generation under the carbon peaking and carbon neutrality goals. At present,the application of biomass co-firing in coal-fired units for power generation in China is still very limited. To further play the role of biomass,a clean and zero-carbon renewable energy,in the new power system,and at the same time take advantage of the flexible coal-fired units,the current status of biomass resources in China,the co-firing options of biomass with coal for coal-fired boilers,and the operation of typical co-firing projects at home and abroad were investigated in detail. It is pointed out that there is a large waste of resources,especially in agriculture and forestry. Biomass co-firing technology in coal-fired units has been widely used abroad,especially in European countries,but has not been applied to large units in China. Some challenges faced by the direct combustion coupled biomass power generation technology of coal-fired units were summarized,including the stable and low-cost biomass raw material supply and process have not yet been formed,mature technology for high-proportion co-firing has not yet been developed,contamination and corrosion on heating surfaces need to be solved urgently,the measurement standards about biomass power generation in co-firing have not yet formed a standard. To improve the flexibility of large-scale coal-fired power plants and reduce CO2 emissions,efforts should be made in the following aspects in the future. By planting energy crops around power plants and on the marginal land,the relative unity and stability of biomass raw materials can be ensured,to avoid the influence of large changes in the properties of raw materials on the operation of the unit. It is necessary to develop high-proportion biomass co-firing technology to ensure that the blending ratio can be adjusted flexibly. Moreover,it is important to explore more advanced biomass power generation measurement methods,which will help determine reasonable subsidies and operation methods for biomass blending and accelerate the formation of a competitive,replicable and disseminated biomass power generation circular economy chain. Then,the demonstration projects according to the proportion of mixed combustion from low to high and bioenergy with carbon capture and storage technology can be carried out to gradually transition thermal power units from raw material carbon reduction to raw material decarbonization to flue gas decarbonization.