The utility model relates to the machining field, in particular to a clamp which comprises a cutter holder body and a cutter support. The cutter holder body form as an arc-shaped slot and a clamping screw hole, the bottom face of the arc-shaped slot is an arc-shaped face extending to the end face of the cutter holder body, and one end of the clamping screw hole is communicated with the side wall of the arc-shaped slot. One end of the cutter support is formed as a cutter slot, a positioning screw hole communicated with the cutter slot is arranged on the side wall of the cutter handle, and an arc-shaped bulge is arranged at the other end of the cutter handle and is matched with the arc-shaped slot. In addition, a cutter holder system which comprises the clamp is also related to. As the cutter handle can rotate along the arc-shaped face of the arc-shaped slot of the cutter holder body, the angle of the cutter support can be changed as requirement, and the angle of the cutter is changed, therefore, the shape of cutting patterns can be changed, the complicated cutter change procedure can be avoided, and the processing efficiency of a piston is improved.