The invention relates to a clamping device for clamping a fastening piece. The clamping device for clamping the fastening piece comprises a clamping jaw, a first biasing member, a clamping body and a driving component, wherein the first biasing member is biased on the clamping jaw; the clamping body is provided with a central axis; a notch for containing the clamping jaw is formed on the clamping body; the driving component is used for driving the clamping jaw to clamp and is supported on the clamping body; the clamping body comprises a first holding element; the driving component comprises a second holding element; the first holding element is matched with the second holding element, which is used for holding the clamping device at a preset clamping state. According to the clamping device provided by the invention, the clamping device can be effectively prevented from being clamped tightly or loosely, and can be kept at the preset clamping state.