Abstract: Excessive fluoride content in water has always been one of the environmental issues of global concern. The calcium fluoride precipitation method produced by calcium-containing substances with the effluent concentration of 8-9 mg/L cannot meet the WHO standard that the fluorine content in drinking water is less than 1.5 mg/L. Based on the concept of mechanochemical activation, the goal of deep defluoridation of drinking water up to standard has been achieved by the Ca₃Al₂(OH)₁₂ synthesized by grinding calcium aluminum hydroxide using planetary milling balls, which is based on a new defluorination mechanism of OH^- and F^- exchange. The prepared material can reduce the fluoride ion concentration from 10mg/L to 0.32 mg/L under the condition of the molar ratio of Ca: Al being 3:2, grinding time of 1h and the stirred speed of 500 r/min. Substituting kaolinite for aluminum hydroxide can also achieve similar deep defluorination, which provides new ideas and feasibility for the high purification of fluorine-containing wastewater.