The invention provides a guide cylinder passing die welding process. The processing flows are that parts such as a dual-hole pipe, a C-shaped pipe, a core rod, a large flange, a small flange, etc., are well fixed through a motherboard and various formworks, thus continuous sections are welded and processed; after that, the continuous section, a shell and the flange are arranged on a soleplate andfixed by bolts through an end surface pressing plate, a supporting block, a middle plate, a middle block and a middle guide plate; furthermore, a lower guide cylinder is welded. By the die tighteningwelding process, the invention avoids the technical problems that all parts are easy to deform in normal welding process, achieves the technical precision which is required by the lower guide cylinder and implements the localization of the equipment.