Aimed at the status in China there are still some people who drink the water with excessive concentration fluorine, what may seriously threat to human health. For example Fuxin is an important production base in Liaoning province, which products aromatic compounds of fluorine. We found that the wastewater had large fluorine ion by testing the wastewater from the plant. It was polluted XiHe River and harmed to people’s health. So we chose the fly ash of Fuxin Plant as the agent to eliminate fluoride，then studied the mechanism of fluorine-removal and the physical properties of fly ash. Eventually we adopted the activation methods and combined the dynamic experiment and static experiment to research the mechanism to eliminate the fluorine with fly ash. The results of the experiment showed that the technology route was feasible which used the modified fly ash to get rid of the fluoride in the wastewater and reached the national emission standards.