Azithromycin is a kind of antibiotic drug widely used in clinic. It has the advantages of wide antibacterial spectrum, little stimulation to gastrointestinal tract and fast oral absorption. It is used by both adults and children. Azithromycin is one of the most commonly used antibiotics for the treatment of bacterial Chemicalbook infection-related diseases in hospitals in China because of its smaller side effects than cephalosporin antibiotics. Azithromycin is a second-generation semi-synthetic derivative of macrolides, which is different from erythromycin in structure. It has inserted a methyl substituted nitrogen at the 9a site of erythromycin lactone ring. And that produces a 15-membered macrolide.