Abstract: Objective： To provide some help for the prevention and the treatment of antibiotic associated diarrhea. Methods： Literatures， reports and research data collected for analysis，to summarize the relevant factors. Results： The occurrence mechanism of antibiotic associated diarrhea is generally believed to be imbalance of intestinal flora. The high risk factors include the use of broad-spectrum antibiotics， antimicrobial therapy for more than 3 days， the elderly， accompanied with chronic diseases，immunocompromised cases，invasive operation and long-term fasting etc. Conclusion： The rational use of antimicrobial agents， the use of strict control of broad-spectrum antibiotics are the keys of preventing antibiotic associated diarrhea. If the illness is not serious， timely discontinuation of antimicrobial agents is effective measure. For critical ill patient， general pseudomembranous colitis， caused by clostridium difficile infection， which should be used with vancomycin or metronidazole， and supplemented with microecologics.For particularly serious case， adrenocortical hormone should be given， so as to improve the toxemic symptoms.