Abstract：The integron is a mobile genetic element which can be located on the chromosome, plasmid or transposon. It can capture, integrate or cut the gene cassette by site-specific gene recombination, so that the horizontal resistance gene transfer enhances bacterial survival adaptability. Class one integron is investigated more extensively, while research on class two or class three integrons is rare, probably due to their presence is not common. In particular, the class three integron is extremely rare, with fewer than ten reported cases. However, the roles of class two and three integrons in the spread of drug resistance cannot be ignored. In this paper, referring to the international related literatures in recent years, we provided a detailed overview for the molecular structures of class two and three integrons and their roles in the transmission of antimicrobial resistance.