An approach is provided for a leash for leashing animals. The leash comprises a strap, an auxiliary loop, a handgrip loop and a snap buckle. The strap reeves a first snap hook at a first end of the leash, which forms an upper-layer belt and a lower-layer belt. The first snap hook is used for attaching to an animal's collar. The auxiliary loop is connected to the lower-layer belt at a second end of the leash and having a ring surrounded the upper-layer belt. The handgrip loop is connected to the upper-layer belt at the second end of the leash. The snap buckle is connected to the auxiliary loop and the handgrip loop, and is configured to release the lower-layer belt selectively toward the upper-layer belt through the first snap hook. Thus, the leash provides the advantage of positive control of the length in a simple fashion.