Aiming at the difficulty in purification of metal pentazolates， the separation and purification of metal pentazolates were studied by precipitation method based on the aqueous solution of sodium pentazolate， which was obtained via C—N cleavage reaction of arylpentazole. Results show that the aqueous solution of sodium pentazolate contains a lot of organic acid salts， as well as inorganic salt impurities such as sodium nitrate and sodium chloride. Compared with N₅ anions， the organic acid salts prefer to precipitate with metal ions in aqueous solution， thus affecting the precipitation of metal pentazolates. Cobalt pentazolate was precipitated from the aqueous solution of sodium pentazolate via acidification， removal of organic acid salts by extraction， and then addition of cobalt chloride. The lower the pH value is， the higher the removal efficiency of organic acid salts is and the higher the purity of cobalt pentazolate is. The optimized separation conditions of cobalt pentazolate are as follows： the pH value is 3， and the molar ratio of cobalt chloride to 4-amino-2，6-dimethylphenol （1） is 0.26∶1. The purity of cobalt pentazolate is up to 97.9% after simple recrystallization as shown by ion chromatography. The applicability of this precipitation method to other metal pentazolates was also studied. Results show that it is also suitable for the separation and purification of iron， ferrous and copper pentazolates.