Method for preparing ceftizoxime sodium

The invention relates to synthetic ceftizoxime acid and a method for preparing ceftizoxime sodium from the synthetic ceftizoxime acid. The preparation process comprises the following steps: slowly adding a crystallization solvent in a crystallization liquid until the crystallization liquid becomes slightly turbid, stopping adding the solvent, slowly stirring and growing crystals for 0.5 hour, continuously adding the residual solvent, and stirring and growing the crystals for 1 hour after the residual solvent is completely added. The product prepared by the optimized process in the invention has remarkably improved quality although the yield is lowered by 1.0-1.5%; and the product crystallization state is obviously improved and the product quality problem of clarity stability in the period of validity is solved.