Abstract: To explore a high-value utilization pathway of flue gas desulfurization (FGD) gypsum, hydroxyapatite (FDG-HAP) was synthesized via a precipitation method using FGD gypsum from a coal-fired power plant as the calcium source. The preparation process was optimized by single-factor experiments and response surface methodology, and the fluoride (F^-) adsorption performance of FDG-HAP from aqueous solution was systematically evaluated. The results showed that pH, oscillation temperature, and CaO particle size were significant factors affecting the yield of FDG-HAP. The optimal conditions were pH=10, oscillation time of 3 h, oscillation temperature of 70℃, and particle size of 600 mesh, under which the yield reached 89.51%, in good agreement with the model prediction. XRD and SEM analyses indicated that FDG-HAP exhibited a short-rod-like nano-agglomerate structure with intact crystalline phase and porous surface, favorable for adsorption. Batch adsorption experiments demonstrated that FDG-HAP exhibited excellent F^- removal efficiency at an adsorbent dosage of 1.6 g/L and pH 4–7. The adsorption process followed the pseudo-second-order kinetic model and Langmuir isotherm model, with a theoretical maximum adsorption capacity of 5.965 mg/g. Mechanistic analysis revealed that the adsorption was governed by the synergistic effects of ion exchange, electrostatic attraction, and surface complexation. This study achieves the concept of “treating waste with waste” and provides a theoretical basis and technical support for the resource utilization of FGD gypsum and fluoride-contaminated water treatment.