The utility model relates to a clamping instrument is used in steam -turbine generator rotor end winding welding, support the clamp and tip support clamp can do not carry out nimble adjustment to the straight line and the tip of coil through the straight line in the instrument, can adapt to different circle coil the arc RADIUS's change, can go on reliably fixedly to near coil welded joint through the intermediate strut clamp, connect the stability that head position put when guaranteeing the welding, the height can be realized to the intermediate strut clamp, the nimble adjustment of angle and position, can adapt to the change of different circle coil welded joint positions, application through this instrument, the welding that can give the rotor coil provides stable, reliable quality assurance.