N. N ′ - carbonyldiimidazole (CDI) is a derivative of imidazole, which has a closed large p-bond in the structure of imidazole and a pair of lone pair electrons in the non bonded SP2 orbital of one nitrogen atom. All these determine that CDI has strong chemical reaction activity, and can react with ammonia, alcohol, acid and other functional groups to synthesize many compounds which are difficult to obtain by general chemical methods. It is widely used as an enzyme and protein binder, as an intermediate of antibiotics, especially as a bonding agent for the synthesis of peptide compounds.