Nickel cobalt manganese hydroxide mainly tests the sulfate ion content. Nickel cobalt manganese hydroxide is mainly used to prepare lithium nickel cobalt manganese oxide, a cathode material for lithium ion batteries. In the process of preparing nickel cobalt manganese hydroxide, a certain amount of sulfate needs to be added, and the sulfate content is an important technical indicator of the finished product. At present, the main methods for detecting sulfate include gravimetric method, volumetric method, spectrophotometry, inductively coupled plasma emission spectrometry and ion chromatography. However, the determination of sulfate content in nickel cobalt manganese hydroxide by ion chromatography has not been reported yet. . Using ion chromatography to determine the sulfate content in nickel cobalt manganese hydroxide, sample pretreatment is the key. This method uses cation resin exchange technology to effectively remove metal ions such as nickel, cobalt and manganese, and at the same time examines the impact of chloride ions on sulfate. Experiments show that this method can effectively determine the sulfate content in nickel, cobalt and manganese hydroxide.