As urbanization accelerates, the volume of sewage sludge continues to rise. Co-firing sludge with coal presents an effective solution for the environmentally sound treatment of sludge. This study provides an overview of the fuel characteristics of sludge, examines advancements in sludge co-firing with coal research, and assesses the impact of sludge co-firing on heat transfer, heating surface integrity, heavy metal emissions, and NOx emissions in coal-fired power plant boilers. The temperature distribution within the boiler is predominantly influenced by the moisture content of the sludge, the co-firing ratio, and the overall boiler load. Adjusting the sludge co-firing ratio or implementing alternative low NOx control methods can partially mitigate NOx emissions. However, an increase in the sludge blending ratio may lead to a slight reduction in coal combustion efficiency. With appropriate sludge moisture levels and a low co-firing ratio, minimal changes are observed in the wear of economizer heating surfaces.