Crystallizing method for ceftiofur sodium

The invention relates to a crystallizing method for ceftiofur sodium. The crystallizing method for the ceftiofur sodium comprises the following steps: after a ceftiofur intermediate reacts with AE active ester, adding water to regulate pH at first; extracting to a water layer; adding ethyl acetate in the water layer; regulating pH and transferring to an ethyl acetate layer; decolorizing by activated carbon; and adding a salt forming agent in the ethyl acetate system to obtain salt. In the crystallizing process, liquid is subjected to phase inversion repeatedly at first, and then is decolorized by the activated carbon, the impurity removal ability is high, sodium salt is synthesized by a one-step method, and the crystallizing method is simple to operate and suitable for industrialized production.