The utility model discloses a heating digestion device. The heating digestion device comprises a digestion pipe, a shell and a connecting pipe, the digestion pipe is arranged in the shell; two ends ofthe digestion tube are respectively provided with a reducing slim tube and extend out of the shell through the reducing slim tubes; a threaded sleeve is fixedly arranged on the peripheral side of thereducing thin pipe, and the two ends of the digestion pipe are fixedly arranged on the shell through screwing of a corresponding nut and one end of the threaded sleeve; the tail end of each reducingslim tube is of a cone frustum structure with a small outer end caliber, one end of the connecting tube is provided with a horn mouth corresponding to the cone frustum structure to be in butt joint with the cone frustum structure, and the connecting tube is fixedly arranged at the corresponding end of the digestion tube by screwing a nut and the other end of the threaded sleeve; an elastic structure is arranged between the flared position of the horn mouth of the connecting pipe and the inner end face of the nut. The heating digestion device disclosed by the utility model is convenient to fixand install and has a better high-temperature and high-pressure resistant effect.