A newmethod has been proposed for the determination of highly concentrated fluorine.In this method,asample of 1.000 mL with high concentration fluorine ion is added for 4 times continuously to a standard solution,whose concentration is 1.000×10-4mol/L and volume is 100.0 mL.The potentials are determined respectively,by using the principle of Gran graphics.The fluorine content in the sample can be calculated from the 5 potentials and relevant volume of the solution.The standard deviation of the 10 times determination is less than 0.005 2.The relative standard deviation is less than 3.4% and the recovery rate of 3 levels and a 6 times determination is 99.3% to 105%.Therefore,this method is simple,convenient,fast,accurate and reliable.Satisfactory results have been obtained in the analysis of industrial wastewater and chemical reagents.