The utility model discloses an on-site assembling and welding device for a large-scale cylinder mixer shell ring. the shell ring comprises a discharging end shell ring, a middle shell ring and a feeding end shell ring; the discharging end shell ring and the feeding end shell ring are arranged at the two ends of the middle shell ring respectively, a plurality of sets of adjusting tools are arrangedbetween every two shell rings, the multiple sets of adjusting tools are arranged on the inner walls of the shell rings respectively, and each set of adjusting tools comprises a misalignment adjustingtool, a butt joint adjusting tool and a connecting piece. The misalignment adjusting tool is used for adjusting the radial misalignment amount of every two adjacent shell rings, and the butt joint adjusting tool is used for adjusting the axial distance between the shell rings. And the connecting piece is used for welding and fixing each shell ring. On the premise of ensuring the on-site installation precision of the whole cylinder body, the problems of difficulty in manufacturing, processing and transporting the cylinder body of the large-scale mixing machine and the like are effectively solved, a crucial role is played in ensuring that the standard reaching production of a large-scale sintering plant is achieved, the manufacturing and transporting cost is reduced, the equipment on-site installation period is shortened, and the labor intensity is reduced.