The invention relates to toltrazuril soluble powder and a preparation method thereof, and the toltrazuril soluble powder is prepared from toltrazuril as a main material and a cosolvent, soluble filler, an essence and the like as auxiliary materials by drying, weighing, crushing, sieving, mixing, qualification inspection and packaging. The toltrazuril soluble powder product has the characteristics of being simple to use, low in cost, rich in flavor and taste, stable in storage, convenient in transportation, good in water solubility and the like, and the efficacy of the toltrazuril on animals can be greatly improved by preparation of a drinking agent.