The invention discloses clay ceramsite cat litter and a preparation method thereof, the clay ceramsite cat litter is prepared from clay ceramsite, the clay ceramsite comprises the following components by mass: 92-96% of clay, 4-5% of coal cinder and 0-4% of an additive, the clay comprises the following components by mass: 15-25% of silicon dioxide, 10-15% of aluminium oxide, 10-12% of ferric oxide, 3-4% of calcium oxide and 4-6% of magnesium oxide, and the loss on ignition is 40-45%. The clay ceramsite cat litter is prepared as follows: mixing a finished clay ceramsite product and a binder with water to obtain a raw material, and performing granulation, low temperature drying, high temperature sintering, water washing dedusting and hot air drying on the raw material. The clay ceramsite cat litter has a solid structure, and numerous inner micropores, so that the clay ceramsite cat litter can adsorb harmful elements and bacteria in environment, can be used for activated biodegradation of harmful substances, and can meet cat litter use requirements; the used clay ceramsite has the advantages of low cost, environmentally-friendliness and no pollution. The preparation method has the advantages of simple realization, large scale production and easy popularization and application.