Many investigations showed that a certain amount of antibiotics was left over in various animal foods. Widespread attention has been paid to the potential risks of antibiotic residues (long-term, low dose) on human intestinal flora. The main cause of antibiotic residues left over in food; the potential impacts of antibiotic residues on human intestinal flora and the regulatory approach of microbiologic ADI in the safety assessment of antibiotic residues in international agencies were described in this review.