〔Abstract〕 Objective To study the pathogen types and drug resistance of hospital acquired pneumonia(HAP) in the respiratory intensive care unit(RICU), and to provide a reference for the empirical anti-infection treatment of HAP. Methods The pathogen types of HAP patients in RICU ward were statistically analyzed, and their resistance to antimicrobial agents and risk factors of MDRO infection were analyzed. Results A total of 156 pathogenic bacteria were cultured from blood and sputum samples of lower respiratory tract of 81 HAP patients, among which 153 pathogenic bacteria were cultured from sputum. Among them, 99(63.46%) gram-negative bacteria, 7(4.49%) gram-positive bacteria and 50(32.05%) fungi were found. A total of 75 strains of MDRO(excluding duplicate strains), accounting for 48.08% of the total bacteria, including 72 strains of gram-negative bacteria(96.00%) and 3 strains of gram-positive bacteria(4.00%), were cultured from the blood or sputum of 48 patients(59.26%). There were significant differences in the days of stay at RICU, days of invasive mechanical ventilation, days of antibiotic use and days of PPI, indwelling central venous catheter, tracheotomy status between MDRO infection and non-MDRO infection(P<0.05). However, there was no significant difference in patients' age, complicated MODS, diabetes mellitus. Conclusion The MDRO infection rate in HAP patients is high, so the possibility of MDRO infection should be fully taken into account when choosing the initial anti-infection regimen, antimicrobial agents should be reasonably used and mechanical ventilation should be withdrawn in time to avoid the long-term use of PPI.