The co-combustion of sewage sludge from coal-fired power plants with coal represents a promising technology for the reduction, stabilization, harmlessness, and resourceful treatment of solid waste sludge. This paper summarizes the co-combustion characteristics of sludge and coal from aspects such as the basic combustion process, influencing factors of combustion properties, slagging/fouling, etc. Sludge can improve coal’s ignition and burnout performance, while coal reduces slagging/ash deposition risk during sludge combustion. The interactions between sludge and coal during co-combustion are analyzed, with the intensity and manifestation of these interactions (synergistic or inhibitory) depending on factors such as the physicochemical properties of the fuels, mixing ratios, and combustion conditions. Additionally, the emission characteristics and control technologies for both conventional pollutants (nitrogen oxides, sulfur dioxide, and heavy metals) and unconventional pollutants (dioxins) during co-combustion are introduced. This mainly introduces the impact of combustion technology on nitrogen oxide emissions, as well as the role of mineral types and their interactions in the emissions of sulfur dioxide, heavy metals, and dioxins.