The invention relates to a diclazuril tablet and a preparation method thereof. The diclazuril tablet comprises the following components by weight parts: 1 part of the diclazuril, 3-5 parts of starch, 1-5 parts of dextrin and 1-2 parts of magnesium stearate. The invention further discloses the preparation method of the diclazuril tablets. The method comprises respectively crushing the diclazuril powder, the starch and the dextrin, uniformly mixing, adding a certain amount of ethanol to prepare into soft materials, sieving to prepare into moisture granules, drying, adding the magnesium stearate, uniformly mixing, sieving the granules to obtain granules of appropriate granularity, and tabletting. The diclazuril tablet provided by the invention is relatively high in bioavailability, and can be fully absorbed by organism after oral administration.