Potassium perfluorobutyl sulfonate is a perfluorinated anionic surfactant with excellent flame retardant properties. It is widely used for flame retardant treatment of synthetic materials, especially as the best flame retardant for polycarbonate materials. Adding a small amount of potassium perfluorobutyl sulfonate (usually 0.06%~0.1%) to the material can significantly improve its flame retardant performance, reaching UL-94V-0 level. This characteristic makes potassium perfluorobutyl sulfonate have broad application prospects in electrical, electronic, and construction fields. In this paper, combustion ion chromatography was used to detect the purity and fluoride ion concentration of potassium perfluorobutyl sulfonate.