Incidence of nonalcoholic fatty liver disease (NAFLD) has been increasing, and NAFLD has become one of the most common liver diseases. Its pathogenesis has not been fully elucidated, and there are no effective medications so far. As the ‘second genome’ of human body, gut microbiota plays an important role in nutrient digestion, absorption and metabolism. Growing evidence has suggested that gut dysbiosis contributes significantly to occurrence of NAFLD and is critical for progression of nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH), liver fibrosis or hepatocellular carcinoma (HCC). Therefore, new strategies for gut microbiota intervention are developed to prevent or treat NAFLD. This review intends to mainly discuss the impacts of intestinal microbial abnormality on the pathogenesis, mechanism and intervention of NAFLD/NASH.