The utility model discloses a hair pin which comprises a clamping board, a net-shaped upper hair bag and a lower hair bag. A connection point is arranged in an adapting position of one end of the inner surface in the clamping board, and the adapting position of the other end of the inner surface in the clamping board is provided with a retaining ring. A fixing connection point is arranged in the adapting position of one end of the inner surface of an elastic strip, and the adapting position of the other end of the inner surface in the elastic strip is provided with a buckling bead. Half of a tooth path of a zipper is arranged on the lateral edge in the clamping board, and the other half of the tooth path of the zipper is arranged on the upper edge of the lower hair bag. The net-shaped upper hair bag is sewed with the left side of the lower hair bag, a row of pressing beads are arranged in the adapting position of the inner edge of the right side of the net-shaped upper hair bag, and a row of buckling holes are formed in the adapting position of the inner edge of the right side of the lower hair bag. In addition, the pressing beads of the inner edge in the net-shaped upper hair bag are flush with the buckling holes in the inner edge of the lower hair bag.