The invention provides a metal wire and a zipper using the same. The metal wire is in a shape of a straight line, and comprises a head part and two leg parts which are connected with the head part and arranged symmetrically, wherein the ends, not connected with the head part, of the two leg parts stretch in opposite directions, a U-shaped groove is formed between the head part and each leg part, mutually symmetric diagonal planes are arranged on two sides, corresponding to the leg parts, of the head part respectively, and the leg parts has sharp corners in the positions of the opening parts of the U-shaped grooves. The zipper comprises a ribbon and zipper teeth arranged on the ribbon in a snap-in manner, and one secondary tooth is arranged between every two chain teeth and is obtained by cutting the metal wire. One secondary tooth is arranged between every two chain teeth, and the distance between two adjacent chain teeth is reduced, so that a sharp object cannot easily pierce the distance or cannot easily take up the ribbon after piercing, the zipper can be prevented from being opened by the sharp object, and the safety is relatively higher.