Abstract: A clamp device and its clamp unit has a clamp unit; a end of the connecting piece is connected with the connecting tube and a front is connected movably to the clip holder, the connecting piece has a frangible portion; the unlocking piece is on the connecting piece and is stop-limited between the connecting piece and the connecting pipe; two clips are connected with the clip holder by a connecting pin; the clip holder is in the clamp tube and can move, the clip stop pin is fixed on the front of the clamp tube to limit the clip holder sliding out from the clamp tube; the clamp tube's wall has spring reeds, which is bent inward and cooperates with the locking surface of the clip holder to form a one-way locking structure; the unlocked piece is provided with a pushing pulling surface and a wedge surface to unlock the spring reed.