In order to avoid the oxidation of ferrous ions to trivalent iron, as well as the inevitable error caused by the different color sensitivity of researchers, the total content of iron(Ⅱ) ions in the LiFePO₄ was determined by the potentiometric titration method, while the total iron content was determined by EDTA complexometric titration and spectroscopy method. The results show that the ferrous ion content in the LiFePO_4provided by factory is 32.703％, of which RSD is 0.059％(n=6), the 95％ confidence interval of iron (Ⅱ) is(32.703±0.062)％, and the content of trivalent iron is 1.235％. The potentiometric titration is a reliable method to measure the content of ferrous ion and trivalent iron in LiFePO₄.