The utility model discloses a clamp used for a centre. The clamp used for the centre comprises a bottom board, a supporting frame and a clamping assembly, wherein the supporting frame is installed on the upper portion of the bottom board in the vertical direction of the bottom board; the clamping assembly is connected to the supporting frame. The clamp used for the centre further comprises a pedestal which can move relative to the bottom board, the pedestal is provided with a step structure correspondingly located below the clamping assembly, the step structure comprises at least two platform parts which are arranged in the vertical direction of the bottom board in a staggered mode, the clamping assembly clamps the top end of the centre, and the bottom end of the centre can abut against one platform part selectively, so that the bottom end of the centre is reliably supported by the platform parts after the centre is clamped and fixed by the clamping assembly, and the centre is reliably clamped by the clamp used for the centre; the clamp used for the centre adapts to clamp centres of different lengths; on one hand, machining operation is convenient, and on the other hand, the machining precision and machining quality are improved.