The utility model relates to a new key fastener, which is composed of a key fastener body, a key fastener ball, a key fastener ring, etc. The key fastener ball is fixed on the key fastener body, the key fastener ring can be sheathed into a key fastener ball groove through a clamp position arranged at both ends of the key fastener ring, and two closed key rings are formed. The clamp position is disengaged from the inner part of the groove by pressing downwards the key fastener ring with a bit force when the key fastener is used. Because of the elasticity function of a wire rope, the key fastener ring can be opened automatically and can be inserted into a lock key, the wire rope then is bent by using the force, the clamp position is sheathed into the groove and is reset, and the function of the key fastener can be finished. The utility model has the advantages of simple structure, novel design and convenient operation, and is suitable for the portability and the use of various people.