Zeolite NaP1 was synthesized by a hydrothermal method from coal fly ash. The possibility of using modified zeolite NaP1 as a material for removing fluorine from drinking water was studied. The effects of adsorption time, the amount of zeolite, and the concentration of fluorine ions on the removal percentage of fluorine ions were studied. The mechanism of the adsorption was also discussed. The removal percentage of fluorine ion increased with increasing adsorption time and with the level of zeolite. The adsorption isotherm could be described by the Langmuir isotherm equation.