The invention extends the connotation range required to be protected on the basis of a previously issued patent ZL200710025045.4, i.e., a nanometer microcrystalline composite filter material and a preparation method thereof, belonging to the field of a water disposal technique material. According to weight percentage, the nanometer microcrystalline composite filter material comprises 3-95 percent of attapulgite clay, 5-80 percent of sepiolite clay, 2-25 percent of kaolinite clay, 2-97 percent of tubular halloysite, 5-75 percent of diatomite, 5-75 percent of natural zeolite (clinoptilolite, mordenite and the like), 0-25 percent of pillared montmorillonite, 0-50 percent of expanded vermiculite, 0-5 percent of expanded perlite and 0-50 percent of active carbon or bamboo carbon powders. All raw materials which are powder shapes are mixed according to proportion and stirred to granulate by adding an inorganic adhesive, then sintered and activated at the temperature of 900-500 DEG C (inert gas is required for sintering and activating the filter material added with active carbon). The nanometer microcrystalline composite filter material has smooth shape, rough surface and uniform particle size, with the diameter of 1-10mm, and is used for biological filter tanks and high-class adsorption filter materials in deep purification systems of drinking water and reclaimed water sewage disposal systems.