The invention relates to a high-molecular compound high-temperature pyrolyzing harmless combustion device. The high-molecular compound high-temperature pyrolyzing harmless combustion device comprisesa feeding device, a high-temperature combustion chamber and a heat exchange device. A dual-fuel feeding system is arranged at the front portion of the high-temperature combustion chamber. A smoke outlet in the upper portion of the high-temperature combustion chamber is connected with a high-temperature pyrolyzing chamber. The outer portion of the high-temperature pyrolyzing chamber is provided with a wall built through heat-preservation materials. The interior of the high-temperature pyrolyzing chamber comprises a secondary air supplementing device, a heat accumulation body, a temperature detector and a high-temperature pyrolyzing chamber fire outlet. By means of the above combustion chamber, plastic type high-molecular compounds can be sufficiently pyrolyzed and combusted to be convertedinto inorganic matter gases, combustion products lose the condition for secondary organic matter synthesizing, and serious pollution brought to the environment due to organic matter combustion is avoided.