A clamping device includes a main sliding plate, a top sliding plate, a pair of clamping plates having a synchronizing bar, and a locking mechanism. The top sliding plate movably connected to the main sliding plate; the pair of clamping plates movably connected to the main sliding plate, the pair of clamping plates and the top sliding plate forming an accommodating space, one end of the synchronizing bar rotatably connected to a respective clamping plate, and the other end rotatably connected to the top sliding plate; the locking mechanism is located in a movement path of the top sliding plate. When the top sliding plate moves in a first direction, the top sliding plate drives the pair of clamping plates to clamp a clamped piece; and the top sliding plate drives the main sliding plate to move in the first direction.