OBJECTIVE： To provide reference for clinical rational drug use and the prevention and treatment of drug-resistance bacteria. METHODS： A total of 148 patients with oral infection after orthodontic treatment were selected from a hospital during Jul. 2011-Jul. 2016. The distribution of pathogenic bacteria and drug resistance were analyzed retrospectively. RESULTS： Among 148 patients with oral infection， 275 clinical specimens were detected， including 209 positive specimens with positive rate of 76.00％. A total of 332 pathogenic bacteria were detected， including 85 Gram-positive bacteria （25.60％） and 247 Gram-negative bacteria （74.40％）. Top 7 isolated bacteria in the list of quantity were Actinobacillus pleuropneumoniae （54 strains， 16.27％）， Porphyromonas gingivalis （41 strains， 12.35％）， Tannerella forsythia （37 strains， 11.14％）， Streptococcus oralis （33 strains， 9.94％）， Klebsiella pneumoniae （30 strains， 9.04％）， Staphylococcus aureus （26 strains， 7.83％） and Pseudomonas aeruginosa （25 strains， 7.53％）. Resistance rates of S. aureus to penicillin G， gentamicin， ciprofloxacin， oxacillin and tetracycline were all in high level （resistance rate＞50％）， but it was sensitive to vancomycin and teicoplanin （resistance rate of 0）. Enterococcus faecalis showed high resistance to penicillin G， erythromycin and oxacillin （resistant rate＞50％）， but was sensitive to vancomycin and rifampicin （resistant rate of 0）. K. Pneumoniae showed high resistance to gentamicin， ciprofloxacin， levofloxacin and cefazolin （resistant rate＞50％）， but was sensitive to imipenem， ceftazidime， cefepime， ampicillin sodium and sulbactam sodium， amoxicillin and clavulanate potassium （resistant rate＜10％）. Resistant rates of P. aeruginosa to gentamicin and levofloxacin were ≥80％， but it was sensitive to aztreonam （resistant rate of 8.00％）. Resistant rate of Escherichia coli to piperacillin was 84.21％， but it was sensitive to imipenem and ampicillin sodium and sulbactam sodium （resistance rate of 5.26％）. CONCLUSIONS： After orthodontic treatment， the pathogens of oral infection are various， mainly Gram-negative bacteria， and their drug resistance is not optimistic. The drugs with high sensitivity to the main pathogens include vancomycin， imipenem and enzyme inhibitor complex preparations， etc. Clinical attention should be paid to the cultivation of pathogenic bacteria and drug sensitivity test； according to the results of drug sensitivity test， targeted antibiotics should be selected to improve the antibacterial effect and delay the emergence of drug-resistant bacteria.