The invention relates to a bag sleeve used for the preparation of target materials by a hot isostatic pressing method, which comprises a hollow square column type bag sleeve body and two sealing bodies which are used for sealing the bag sleeve body. The bag sleeve is characterized in that at least one lateral edge of the body is provided with a frilling; the number of the frilling is at least one, and two frillings are preferred and four frillings are more preferred. The body is formed by bending one or a plurality of plates and welding two ends. The invention also relates to a method which adopts the bag sleeve for producing target materials.