The invention belongs to the technical field of cat litter process, and in particular relates to aromatic sterilization type birch compound cat litter and a preparation method thereof. In a processing process, birch emits a slight fragrant and sweet smell; the cat litter prepared by the method has the fragrance of the birch, is low in density, has good water absorption, bulkiness, antibacterial property and adsorption property, is biodegradable, green and environmental-friendly, and can effectively improve the living environment of cats; the regularly cleaned cat litter can play a role in improving the soil after being put into the soil, and can be used as organic fertilizer so as to save resources due to containing animal feces. According to the preparation method provided by the invention, the birch is compounded with filling type wood, an antibacterial agent, sodium hydrogen carbonate and a binding agent for realizing a synergistic effect; a vertical ring die granulator is adopted, so that the prepared cat litter is uniform in particle size, tiny in aperture and good in bulkiness, and the strong absorption of the cat litter for the odor of the feces is guaranteed; furthermore, the yield is high, and the production efficiency is increased.