The invention belongs to the field of drug synthesis and in particular relates to a sulbenicillin sodium intermediate and a method for preparing sulbenicillin sodium thereform. The method specificallycomprises the following steps: reacting phenyl-2-sulfoacetic acid and isopropenyl acetate to produce an intermediate Z1; reacting the intermediate Z1 and a solution 6-APA, and further crystallizing out sulbenicillin sodium with sodium iso-octoate. Compared with the traditional acyl chloride method for preparing the intermediate, the method for producing the intermediate Z1 in the invention has the advantages that the problem that the raw materials and intermediate are damaged due to moisture absorption is solved, emission of acid gases such as sulfur dioxide and hydrogen chloride produced during acyl chloride preparation is reduced, the process is simple and easy to operate, and the solvent is convenient to recycle. The method for preparing sulbenicillin sodium from the intermediate Z1 inthe invention has the advantages of being low in cost, high in yield and excellent in quality, the prepared sulbenicillin sodium has the purity of 99%, and the method is mild in reaction condition, easy to operate and suitable for industrial production.