Due to the increased flanging of the side end of the step ring packing, not only the mechanical strength of the packing ring can be increased, but also the directional probability of the packing is increased due to the destruction of the symmetry of the packing structure. And because of flanging, the contact between packing ring gap changes from linear contact to point contact during packing. In this way, not only the gap between packing particles is increased, the resistance of gas through the packing layer is reduced, but also these contact points can be the convergence and dispersion point of liquid flow along the packing surface, so as to promote the surface renewal of liquid film, which is conducive to the improvement of the mass transfer efficiency of packing.