The invention relates to a stainless steel exhaust fume collecting hood welding, bonding and re-welding fixture which is characterized by comprising a platform, a left-side external pressing block, aright-side external pressing block, a left front external pressing block, a right front external pressing block, a left internal pressing block, a right internal pressing block, a middle internal pressing block and a middle external pressing block. The platform is used for placing a stainless steel exhaust fume collecting hood; the stainless steel exhaust fume collecting hood is provided with a left folding edge, a right folding edge and a front folding edge; a positioning structure is arranged on the platform; the left-side external pressing block is driven by a left outboard drive structure;the right-side external pressing block is driven by a right outboard drive structure; the left front external pressing block is driven by a left front drive structure; the right front external pressing block is driven by a right front drive structure; the left internal pressing block is constrained on the platform, can slide move and right, and is driven by a left inner-side drive structure; theright internal pressing block is constrained on the platform, can slide move and right, and is driven by a right inner-side drive structure; the middle internal pressing block is fixed onto the platform; a locating pin is fixed onto the middle internal pressing block; and the middle external pressing block is arranged in the middle of the front part of the platform and is driven by a middle drivestructure. According to the fixture, the process of welding, bonding and re-welding is completed, so that the fixture cost is reduced, meanwhile, the process is simplified, and the time and the cost are reduced.