Abstract: The cobalt salt aqueous electrolyte with a high concentration and purity of cobalt is the key to the preparation of high-purity or ultra-high-purity metallic cobalt by electrolysis or electrolytic refining. To get such aqueous electrolyte, the core is to separate cobalt and nickel ions as much as possible. The main separation methods include ion exchange, extraction chromatography, membrane separation and solvent extraction, etc. At present, the researches mainly concentrate on sulfate aqueous electrolyte system containing a high concentration of nickel ion and a low concentration of cobalt ion. Ion exchange and extraction chromatography are effective means to realize the effective separation of the two ions, and it is easier for solvent extraction to achieve scale application. The research is mainly aimed at the development, modification, combination of the organic extractant and adsorbent materials, and corresponding improvement of their separation process. In this paper, the research on the separation of cobalt and nickel ions in the aqueous electrolyte is reviewed. And the prospect of this process is also discussed.