Comet fiber filter material is a new type of filter material, which is formed on the basis of bundling fiber balls. It is not easy to disperse. It has the advantages of high filtration precision and large amount of sewage interception of fiber ball filter material, as well as the advantages of particle filter material backwashing and less water consumption. The porosity distribution of filter bed formed by the filter material is close to the structure of ideal filter material. The porosity distribution in the cross section of the filter bed is uniform, which ensures the consistency of the size of the water channel during filtration. The direct effect is that the sewage interception is uniform, and the water short circuit phenomenon is avoided. In the vertical section of the filter bed, the porosity distribution gradually decreases from top to bottom, and the porosity distribution along the vertical section of the filter bed is in a gradient of large up and small down. This structure is very conducive to the effective separation of suspended solids in water, that is, the particles desorbed from the upper part of the filter bed are easy to be trapped and retained in the lower narrow channel filter bed.