Method for refining sugammadex sodium

The invention discloses a method for refining sugammadex sodium. The method comprises the following steps: liquid separating and refining a crude sugammadex sodium product in a poor solvent/water system, preferentially separating out and enriching dimer impurities which are difficult to remove into solids to remove, separating (liquid separating and filtering) to obtain a mother liquor, further adding a poor solvent for crystallizing to obtain high-purity sugammadex sodium. According to the refining method provided by the invention, the contents of dimer impurities A and B can be effectively reduced; the total purity of the refined sugammadex sodium is greater than 99.5%, the impurity A is not detected in the finished product, the content of impurity B is less than 0.1%, the content of other single impurity is less than 0.1%, the adopted reagents are all conventional and easy to obtain, the operation is simple and safe, and the method is very suitable for industrial amplification underconventional production