The invention relates to a high temperature methanation device, which comprises a methane reactor for synthesizing methane and a heat exchanger for exchanging heat of gas exhausted by the methane reactor and is characterized in that the methane reactor and the heat exchanger are arranged in the same pressure container casing, a cooling device is arranged on a pipe, gas channels of all sections of the heat exchanger are sequentially in series connection through expansion joints with cooling devices, two ends of a cooling medium channel of each section of the heat exchanger are respectively connected with an corresponding upper collection tank and a corresponding lower collection tank, all sections of the heat exchanger are suspended in the casing through connection between drainage channels and the lateral wall of the casing and inlet channels and the lateral wall of the casing, and gaps are formed between each section of the heat exchange and the lateral wall of the casing at intervals. An outlet of the air channel of the hat exchange is communicated with an outlet of the casing. The methanation device is directly connected with a steam generation system. A waste pot and a superheater in the steam generation system are integrated, thereby resolving the problem that a steam generator and a steam superheater are difficult to choose in type.