Irritable bowel syndrome is one of the most common functional gastrointestinal disorders,of which the pathogenesis is not yet clear. Recently,the effects of intestinal microflora get more and more attention in the pathogenesis of irritable bowel syndrome. Epidemiological proof and clinical proof indicate that the infection of gastrointestinal can induce post infectious irritable bowel syndrome, some patients exist small intestinal bacteria overgrowth and dysregulation of intestinal bacteria,antibiotic can relive the symptoms of some patients with irritable bowel syndrome. So someone consider that using probiotics may be a beneficial and reasonable method for the patients of irritable bowel syndrome.