Method for purifying doripenem side chain of doripenem drug intermediate

The invention discloses a method for purifying the doripenem side chain of a doripenem drug intermediate. The major impurity compound doripenem side chain disulfide in the doripenem side chain synthesis of a doripenem drug intermediate is removed in a recrystallization way; and the purity of the doripenem side chain is increased so as to provide reliable guarantee for improving the quality of doripenem drugs.