The invention discloses a clamping mechanism for roller processing and a using method thereof. The clamping mechanism is provided with three blocking slots, three bulges, three clamping blocks and three U-shaped slots, wherein the U-shaped slots are adaptive to the bulges, and the blocking slots are adaptive to the clamping blocks, so that the clamping blocks are conveniently mounted, are mountedmore compactly, and are more stable in use. The using method of the clamping mechanism comprises the following steps: inserting a roller into an arc-shaped slot, starting a gas cylinder III, pushing apush rod to move by a piston rod, pushing a push block to move by the push rod, pushing a circular ring to move by the push block, pushing a support rod II and a slide sleeve to move, sliding the slide sleeve in a slide hole I, pushing the front ends of the clamping blocks to extrude the roller, pulling elastic parts to be the longest at the rear ends of the clamping blocks through cushion plates, and clamping the roller through the three clamping blocks. The clamping blocks, springs, the elastic parts and the cushion plates are arranged, so that the clamping mechanism has good buffer property, and is convenient in fixing the roller; and meanwhile, rollers of different diameters are conveniently fixed, so that the range of application is wide.