Sulfa drugs developed rapidly in the 1930s, and there had been more than 20 species of the drugs for the clinical application. the status of sulfa drugs in chemotherapeutic agents declined after 1940s due to the occurrence of penicillin and other antibiotics. But sulfa drugs, whose antibacterial activity will be enhanced when combined with trimethoprim the antibacterial synergist, are still commonly used antibacterial drugs for the advantages of broad antibacterial spectrum, enabled to be administered orally, more rapid absorption. Clarifying the mechanism of the action of sulfa drugs established anti-metabolic theory and opened up a new way for the development of new drugs. Currently there are sulfadiazine and sulfamethoxazole that are used most widely in clinical.