The invention discloses an active alumina/active carbon composite material and a preparation method thereof. The composite material comprises the following ingredients: 70-90 weight portions of sludge, 10-30 weight portions of active carbon, and 15-35 weight portions of binder, and is prepared by uniformly mixing, pelleting, aging, molding, drying in the air, sintering, rinsing and drying. Using sludge as raw material has an important meaning to environmental protection and recycling of waste. The invention has the advantages of simple preparation method, easy obtainment of raw material, and low cost, and can be widely applied in the fields of industry, agriculture, environmental protection, air cleaning, water treatment and the like.