Abstract: A preparation method for selenium covered basic copper chloride includes the steps of: (a) adding crystalline basic copper chloride (TBCC), water and stabilizer in a reactor; adding sodium hydroxide solution with stirring; reacting to form a hydroxyl-modified crystalline basic copper chloride after discharge, washing, and negative pressure leaching; (b) adding the hydroxyl-modified crystalline basic copper chloride and water in the reactor, adding selenous acid with stirring; adding copper sulfate pentahydrate after reaction; forming selenium covered basic copper chloride comprising crystalline basic copper chloride, basic cuprous selenide, and basic cupric sulfate after discharge, rinsing, negative pressure filtration, and drying. The selenium covered basic copper chloride is used as feed addictives of trace elements having nonhygroscopic property, good liquidity, and stable chemical property.