According to an elastic waist belt, an elastic insertion sheath structure is arranged on the waist belt. The elastic insertion sheath structure comprises a sheath shell connecting end, a sheath tongue connecting end and elastic connecting woven tape, wherein the sheath shell connecting end and the sheath tongue connecting end correspond to each other and are connected through the elastic connecting woven tape. The sheath shell connecting end is of an empty groove structure. Due to the size and the shape of the sheath tongue connecting end, the sheath tongue connecting end can be inserted into an empty groove of a sheath shell connecting piece. When the sheath shell connecting end is away from the sheath tongue connecting end, the elastic connecting woven tap provides elastic force so that the sheath shell connecting end can be drawn close to the sheath tongue connecting end. The strength of the elastic waist belt can naturally extend when external force is exerted on the elastic waist belt, and therefore a person can feel comfortable and can not have a sense of pressure, and the elastic waist belt can be easily worn or taken off. The elastic waist belt has the advantages of having the adjustable fixed length and the fixed model, and being easy to adjust and comfortable and convenient to use.