Method for preparing cefdinir

The invention provides a method for purifying cefdinir. The method comprises the following steps: enabling crude cefdinir to react with alkaline to form a water soluble cefdinir alkali metal salt; (2) adding an antioxidant or an oxidant to the aqueous solution of the cefdinir alkali metal salt, and then decoloring through active carbon; and (3) acidifying the solution to obtain high-purity cefdinir white crystal powder. The method is an improved method for refining cefdinir, is simple and feasible, has low cost, and is applied to various situations needing purification of cefdinir.