Simple diameter-variable clamp holder

The utility model relates to a simple diameter-variable clamp holder which comprises a clamp shell and two braking clamping blocks which are arranged in the clamp shell in a sleeved mode and are oppositely arranged, a clamping groove is defined between the two braking clamping blocks, threaded holes which are reversely arranged are formed in the opposite ends of the two braking clamping blocks, through holes are formed in the other opposite ends of the two braking clamping blocks, and the two braking clamping blocks are arranged in the clamping groove in a sleeved mode. The screw penetrates through the outer surface of the clamp shell and is screwed on the threaded hole, the polish rod penetrates through the outer surface of the clamp shell and penetrates into the through hole, and the screw is screwed to drive the two brake clamping blocks to be close to or away from each other so as to adjust the size of the clamping groove. And the tail ends of the screw rod and the polished rod are fixed with the fixture