The invention relates to a technology for preparing calcium iodate by taking brine rinsed with crude zinc oxide as a raw material. The technology comprises the following steps: (1) evaporating and concentrating the brine rinsed with crude zinc oxide, and performing centrifugation to obtain iodine-containing brine; (2) adding hydrochloric acid to the iodine-containing brine, then dropwise adding hydrogen peroxide, when the pH value of the system is 1-2 and no iodine is formed, stopping reacting, and performing filtration to obtain iodine precipitate; (3) adding alkali liquor to the iodine precipitate, and when the pH value of the reaction liquid is 8-9, performing stirred dissolution and filtration to obtain an iodine-containing solution; (4) preparing a chlorate solution, then dropwise adding the iodine-containing solution to the chlorate solution, when the pH value of the system is less than or equal to 1, the temperature is 85-90 DEG C and the reaction liquid is colorless, stopping reacting, and performing filtration to obtain a hydrogen iodate solution; and (5) adding calcium salt to react to produce calcium iodate, filtering the calcium iodate, washing filter cakes, and then, drying the washed filter cakes to obtain a finished product. Technological processes realize the closed production of iodine, the technology and equipment are simple, the economic cost is low, and thetechnology is suitable for industrial automatic production.