Abstract: OBJECTIV To conduct the combined drug susceptibility testing for drug-resistant Acinetobacter baumannii so as to provide guidance for clinical drug combination. METHODS The patients with hospital-acquired pneumonia who were hospitalized in critical care medicine department and respiratory department from Jun 2015 to Sep 2016 were enrolled in the study. Totally 30 strains of drug-resistant A.baumannii were screened out by the clinical laboratory, the culture plates containing fosfomycin sodium were made by using agar dilution combined with disk diffusion method, and the drug concentrations were 0mg/L,70mg/L,140mg/L,and 280mg/L, respectively. The plates were stuck with drug susceptibility testing pasters: cefoperazone-sulbactam, cefoperazone, imipenem cilastatin sodium, amikacin, levofloxacin, piperacillin; the conventional culture was carried out. RESULTS As for fosfomycin sodium in combination with cefoperazone-sulbactam, the A.baumannii strains that were susceptible to the drug was increased from 0 (fosfomycin sodium concentration 0mg/L) to 7 (fosfomycin sodium concentration 70mg/L) and 19 (fosfomycin sodium concentration 140mg/L), showing significant synergistic effect P<0.05. As for fosfomycin sodium in combination with levofloxacin, the A.baumannii strains that were susceptible to the drug was increased from 0 (fosfomycin sodium concentration 0mg/L) to 0 (fosfomycin sodium concentration 70mg/L) and 8 (fosfomycin sodium concentration 140mg/L), showing significant synergistic effect P<0.05. However, fosfomycin sodium in combination with cefoperazone, imipenem, amikacin, or piperacillin did not show significant synergistic effect. There was significant difference between the fosfomycin sodium in combination with cefoperazone-sulbactam and fosfomycin sodium in combination with levofloxacin (P<0.05). CONCLUSION As for the multidrug-resistant A.baumannii, the fosfomycin sodium in combination with cefoperazone-sulbactam and fosfomycin sodium in combination with levofloxacin show significant synergistic effect, however, the former is better.