The invention relates to a gasification furnace capable of preventing dreg formation and efficiently recycling heat energy. The gasification furnace comprises a reaction chamber, a waste boiler cooling chamber located below the reaction chamber and a chilling chamber located below the waste boiler cooling chamber, wherein the reaction chamber is used for gasifying coal to obtain crude coal gas andash dreg; the waste boiler cooling chamber comprises a radiation waste boiler; the radiation waste boiler comprises a cylindrical radiation waste boiler and a conical radiation waste boiler connectedto the bottom of the cylindrical radiation waste boiler, and forms a longitudinal channel for recycling the crude coal gas and the heat energy of the ash dreg; the chilling chamber is located at thelower part of the radiation waste boiler and comprises a chilling ring, a descending pipe, a dreg bath tank and a bubble breaking plate. The gasification furnace can ensure that the level of ash content is relatively low when the heat generated by gasification is efficiently recycled, and the problem that the radiation waste boiler is easily blocked and corroded by the ash dreg in an operation process can be prevented.