Abstract: Ion chromatographic method for determining PO43-，Cl-，and F- of potassium dihydrogen phosphate（KDP） was established.The three anions can be separated and determined simultaneously in 12 min.The purity of potassium dihydrogen phosphate can be calculated through the content of PO43-.Under the optimal experimental conditions，the standard curves of three anions were obtained，the correlation coefficient r was 0.999 2~0.999 9；the detection limits were in the range of 0.051~0.30  g/mL；the average raddition standard recovery rates were at 95.6%~104.5%，and the relative standard deviations were at 3.1%~4.9%.The difference analysis on the established method and standard method（HG 2321—1992） indicated that there was no significant difference between them.The simple and fast method has advantage of good reproducibility.It is especially suitable for the process control of production of KDP.

Key words: ion chromatography, KDP, purity, F-, Cl-