The invention relates to a biological deodorization filling material and a preparation method thereof. The filling material is circular particulate matters of which the diameters are from 3 cm to 6 cm, and is prepared from uniform mixing and pelletization of the following components in parts by weight: 60-80 parts of decomposition garbage in a domestic waste composting plant, 10-30 parts of straws, 20-40 parts of activated sludge in an aerobic pond of a domestic sewage processing plant, 1-15 parts of calcium carbonate, 5-30 parts of nitrifying bacteria culture solution, 5-30 parts of sulfidation bacteria culture solution, 0.5-2 parts of trace element I and 0.5-2 parts of trace element II. The filling material has the characteristics that the filling material can quickly gather sulfidation bacteria and nitrifying bacteria; the sulfidation bacteria can remove H2S in odorous gas quickly; the nitrifying bacteria can remove NH3 in the odorous gas quickly; the filling material contains culture solution of microbe deodorization bacteria, so that the filling material can quickly and efficiently gather deodorization bacteria; basicity supplement is not needed in an operation process; the removal efficiencies of the H2S and the NH3 in the odorous gas are greatly improved.