The unburned spherical low-density zeolite composite paddings 4～8 mm in particle size with natural zeolite as the main raw material, cement as the binder, spherical particles of polystyrene as the core were prepared through the procedure of compounding, sphere making, screening, and maintenance. Based on testing the void fraction, apparent density, compression strength and other characteristics of materials in the preparation, the authors have concluded the optimal conditions of process combination in the preparation of low density composite paddings as follows. Weight proportion of zeolite∶cement is 75%∶25% and maintenance is 7～10 d under normal conditions. Under such conditions, the void fraction is 47.4%, apparent density is 1.23 g/cm³, compression strength is 61.5 N, and piled density is 0.647 g/cm³. Scanning electron microscopy clearly shows that before the biofilm formation the surface is rough, and the interior has numerous pores, whereas after the biofilm formation, a large number of microbes exist on the surface and in the internal. The number of microbes is twice that of the fly ash biological filter. When the method is applied at the ambient temperature below 15℃ under BAF biofilm, the ammonia and nitrogen removal rate of the unburned spherical low-density zeolite composite paddings even reaches 96%. The high ammonia and nitrogen removal efficiency shows a good prospect of the composite paddings in advanced treatment of wastewater denitrification.