Abstract: Gasification technology is one of the most promising thermochemical conversion technologies. Gasification technology can convert sludge and other waste into valuable gases such as H₂ and CO, achieving waste resource utilization, harmless treatment, and large-scale treatment. This article investigates the synergistic gasification reaction between sludge and H₂O/CO₂ using thermogravimetric and fixed bed devices and analyzes the gasification reactivity of sludge organic matter and the distribution of combustible gas products. The research results indicate that the CO₂ gasification reaction rate and carbon conversion rate of sludge coke gradually increase with the temperature increase, but tend to stabilize after reaching a certain temperature. When the gasification reaction temperature is raised from 900 ℃ to 950 ℃, the maximum reaction rate is shortened from about 5 minutes to instantaneous completion. This change indicates that in the early stages of the reaction, the more reactive carbon components in the sludge char can quickly react with the gasifying agent. However, for those carbon components that are difficult to respond to, their reaction with gasification agents requires a longer time. When sludge coke reacts with H₂O, it cannot be completely gasified until 1000 ℃, with a carbon conversion rate of 92.34%. The main reason for this phenomenon is the high ash content in the sludge, which hinders the effective contact between the gasifying agent and organic substances in the sludge during the reaction. With the increase in temperature, the yield of H₂ increased from 58.84 L/kg to 242.97 L/kg, the yield of CO increased from 10.28 L/kg to 152.41 L/kg, indicating that the reaction rate was getting faster and faster. When the H₂/CO ratio decreased from 5.72 to 1.59, the water-gas shift reaction weakened with the increase of temperature. Meanwhile, when the gasifying agents are H₂O, CO₂, and H₂O/CO₂, the gasification carbon conversion rates of sludge coke are 95.57%, 91.16%, and 100%, respectively. At 900–950 ℃, the release rate of H₂ decreased from 10.48% to 2.71%, and the release rate of CO decreased from 72.44% to 1.01%, indicating that the carbon in the sludge is about to be completely gasified, which is similar to the results of carbon conversion rate. It can be seen that when the gasifying agent is a mixed gasifying agent, all carbon in the sludge coke reacts completely, indicating a positive synergistic process between sludge coke and CO₂/H₂O. The main reason is that the ash content in the sludge plays a significant catalytic role in the H₂O/CO₂ mixed gasifying process, which promotes the gasification reaction and enhances the interaction between sludge coke and gasifying agent, thereby achieving a positive synergistic effect.