The invention discloses a clamp for turning eccentric shafts. The clamp comprises a chassis, a swing disc, a three-claw chuck and a baffle, the three-claw chuck is fixed to the middle portion of the swing disc, the lower end of the swing disc is hinged to the chassis, an arc-shaped sliding groove is formed in the upper portion of the swing disc, a positioning pin fixed to the chassis is located inthe arc-shaped sliding groove, the baffle abuts against one side of the swing disc, the lower end of the baffle is hinged to the chassis, one end of an adjusting rod is rotationally connected to theupper end of the baffle, the other end of the adjusting rod is in screw joint to an adjusting support, the adjusting support is fixed to the chassis, and a locking bolt arranged on the chassis upwardspenetrates the swing disc to be connected with a locking nut in a matched manner. Operation is simple, time and labor are saved, the production efficiency is obviously improved, and the product quality is greatly improved.