Abstract: The treatment of fluorine-containing industrial wastewater is a hot issue for many enterprises, especially the difficulty in meeting the standard for coagulation-precipitation effluent. Magnetic microporous lanthanum formate defluorinator (FML) was prepared using the hydrothermal synthesis method. The influence of different lanthanum contents and reaction conditions on fluorine adsorption was investigated by single factor experiment. The crystal structure, surface adsorption sites, specific surface area and pore size distribution, and surface charge characteristics of FML were characterized by X-ray diffractometer (XRD), field emission scanning electron microscopy- energy dispersive spectrometer (FESEM-EDS), microporous physical adsorption analyzer (BET), Fourier transform infrared spectrometer (FTIR), and zeta potential analyzer, and the adsorption mechanism of FML on fluorine was discussed. The results showed that: The fluoride adsorption rates of FML0.5, FML1.0, FML1.5 and FML2.0 gradually increased, all of which could reduce the fluorine concentration in fluorine-containing wastewater from 5.0 mg/L to less than 1.0 mg/L, and meet the fluoride concentration limit (1.0 mg/L) in Class Ⅲ standard of Environmental Quality Standards for Surface Water (GB 3838-2002). Under the reaction conditions of pH 6.32, temperature 318 K, 10.0 mg/L of initial fluorine concentration and 0.2 g/L of FM2.0, the removal rate of fluorine by FML2.0 was more than 99%, and the maximum adsorption capacity of fluorine was 138.3 mg/g. The decreasing rule of anion effect on fluorine adsorption was \mathrmCO_3^2- >\mathrmSO_4^2- >Cl⁻. The removal mechanism of fluoride ions was mainly achieved by electrostatic attraction, which adsorbed onto the surface of FML and replaced the hydroxyl groups at the adsorption sites on the FML surface. The adsorption kinetics and thermodynamics of fluorine by FML2.0 followed the pseudo-second-order kinetic reaction model and Langmuir model, respectively. The adsorption process mainly consisted of chemisorption and monolayer adsorption, belonging to endothermic reactions. The higher the temperature, the more favorable the adsorption. FML2.0 was applied to the treatment of fluorine-containing industrial wastewater by coagulation and sedimentation. When the dosage of FML2.0 was 0.2 g/L, the fluorine concentration in the effluent was reduced from 9.80 mg/L to 0.78 mg/L after 60 min of reaction, indicating that the defluorinator has a good application prospect.