The invention provides a clamp. The clamp comprises one first clamping component and one second clamping component; the first clamping component is provided with a first clamping part; the second clamping component is pivoted at the first clamping component; the second clamping component is provided with a second clamping part; the second clamping part is concavely provided with a clamping groove;the clamping groove extends in a direction parallel to the radial direction of a pivoting shaft; and one deep tooth is convexly arranged inside the clamping groove. By virtue of the structure, the clamp can effectively prevent the situation of slip generated when a screw head is twisted by the clamp.