The invention relates to a reaction kettle that processes the waste tyre and waste plastics by cracking, comprising a reaction kettle cylinder; wherein, a hot air layer is arranged outside the reaction kettle cylinder and is communicated with a hot air inlet and a hot air outlet. A feed opening is arranged above the reaction kettle while a discharge opening is arranged below the reaction kettle. An air outlet for the gas produced during reaction is arranged on the sidewall of the reaction kettle cylinder, and is connected with a dewaxing device. An alkali material injection port is arranged at the side of the feed opening above the reaction kettle cylinder. The alkali powder or lye can be added into the reaction kettle intracavity through the alkali material injection port to remove the acid gas produced and thus prolonging the service life of the device. The gas after reaction is dewaxed by the dewaxing device when removed, which enables the wax to be completely converted into fuel oil and the yield of the product is improved greatly.