A clamping structure is assembled in a handpiece. The clamping structure includes a connecting member for clamping a dental tool and a controlling member. Two or more clamping portions are disposed on the connecting member, and a distance between the clamping portions is changeable due to a control over the clamping portions. The controlling member corresponds to the connecting member and is abutted against the clamping portions. The controlling member can be moved relative to the clamping portions to form the control over the clamping portions so as to allow the clamping portions to clamp or to release the dental tool. A tungsten carbide coating layer is disposed on a contact surface of the controlling member, contact surfaces of the clamping portions, or both.
