Abstract: High fluoride (F⁻) level in coal mining water has became one of the major challenges which restricts the green development of coal mining in western China. To resolve this problem, a mechanochemical one-step solid phase reaction method for preparing aluminum modified activated carbon (AC-Al) was developed, which avoid production of liquid and solid waste as well as long preparation period compared with conventional hydrothermal modification methods, as a result, fluoride was removed from coal mining water fast and efficiently. The effects of Al addition amount, pH, coexisting anions and organics, adsorbent dosage and reaction time on the fluorine removal capability were studied. The fluoride removal efficiency of AC-Al was proportional to the addition amount of Al, and when Al addition amount was 0.32 g, the fluoride removal from simulated water reaches >80% within 30 s. Over 80% of fluoride was removed from water under pH from 3 to 10, which showed good applicability of AC-Al for different water quality. The adsorption process fitted well with the Langmuir model, that means monolayer adsorption, and the theoretical saturated adsorption capacity of AC-Al was 1.47 mg/g. The adsorption process conformed to the pseudo-first-order kinetic model. Fluoride removal was not affected by sulfate, chloride and bicarbonate ion (1000mg/L), as well as humic acid, but the adsorption efficiency decreased by 21% and 11% respectively when the chloride and bicarbonate ion concentration was3000mg/L. The removal rate of fluoride in the coal mining water reaches 84.9% when AC-Al was 10 g/L within 30 s, and the concentration was reduced from 4.85 mg/L to 0.73 mg/L, which met the requirements of “Environmental Quality Standard for Surface Water” (GB3838-2002) (Class I, II, III). The fluoride adsorption process in coal mining water conformed to the pseudo-first-order kinetic model as well. The element mapping of AC-Al showed that Al was uniformly loaded on the surface of activated carbon; and fluoride was evenly adsorbed on AC-Al which was similar to Al distribution, indicating that Al was the active site for fluoride adsorption. According to the results of X-ray photoelectron spectroscopy, the binding energy of Al increased from 74.20 eV to 74.28 eV and 77.80 eV ( two binding states), implied that the Al-FOH, Al-F were formed on the surface of AC-Al after adsorption, which is the direct cause of rapid and stable defluoridation. Meanwhile,there was very little Al dissolution from the adsorbent (0.34 μg/g). The aluminum modified activated carbon prepared by mechanochemical method had good defluoridation capacity, which could provide a new universal technical route for the preparation of adsorbents, and a support to remove fluoride from coal mining water.