Abstract: With the increasing use of broad-spectrum antibiotics over the past two decades, the proportion and severity of Clostridium difficile-associated diarrhoea (CDAD) is increasing in health-care settings. Antibiotics remain the most important risk factor for CDAD, due to their limiting the ability of the gastrointestinal flora to inhibit C.difficile colonization. The antibiotics metronidazole and vancomycin have been showed to be effective in the treatment of CDAD. Despite appropriate antibiotic treatment, lots of patients with CDAD will experience disease recurrence. The use of probiotic bacteria to enhance the host flora, as either primary or secondary prophylaxis will be an effective. The currently accepted mechanism of inhibition of CDAD was as follows:inhibit of the growth of C.difficile, inhibit of the adhesion of C.difficile, stimulate the immune system. The diarrhea pathogenesis and epidemiological studies of C.difficile, as well as probiotics as the drug used in the treatment of CDAC, mechanism of probiotics inhibit the CDAC were described in this article.