An LED lens and a light emitting device using the same are disclosed. The LED lens comprises a light incident surface, a light emitting surface, and a bottom surface. The light emitting surface includes a first recession portion disposed at the central thereof and a protrusion portion connected to the outer periphery of the emitting recession portion. The light incident surface comprises a first optically active area and a second optically active area. The first optically active area is disposed at the central of the light incident surface, and has a second recession portion; the second optically active area is a concave surface connected to the first optically active area. The LED lens satisfies specific conditions. The LED lens distributes a light beam emitted from the light emitting device to form an even light pattern.