The invention relates to cat litter prepared from dry bean dregs and a preparation method thereof, wherein the cat litter is used for burying excrement and urine of pets. The cat litter is prepared from the following components through a series of processes including crushing, mixing and forming according to weight ratio: 5-90 parts of dry beam dregs, 10-90 parts of plant adhesive, 20-80 parts of filling agent, 0.1-10 parts of releasing agent, 0.1-5 parts of surface active agent, 0.01-3 parts of preservative, and 1-10 parts of deodorant. According to the invention, the cat litter prepared by the preparation method provided by the invention has the advantages of being wispy and hollow in surface, low in structural density, light in weight, higher in water absorption speed and better in water absorption performance; compared with other cat litters, the cat litter has the advantages of being more saving in use amount and higher in cost performance; after being used, the cat litter can be directly washed away through a sewer and cannot be blocked; the cat litter is convenient to clean; and the cat litter provided by the invention has the advantages of being environment-friendly, non-toxic, pollution-free, strong in absorption performance, simple in production process and free from wispy dust in production and transportation processes and has a deodorization function.