OBJECTIVE To evaluate the efficacy and safety of ceftazidime/avibactam （CAZ/AVI） combined with amikacin （AMK） in the treatment of carbapenem-resistant Enterobacteriaceae （CRE） severe pneumonia. METHODS A retrospective cohort study was conducted on 240 patients diagnosed with severe pneumonia caused by CRE infection in the intensive care unit （ICU） of the Affiliated Hospital of Xuzhou Medical University from January 2022 to December 2024. The patients were divided into a combination group （CAZ/AVI combined with AMK， n＝136） and a control group （CAZ/AVI alone， n＝104）. The 28-day mortality rate， clinical efficacy，mechanical ventilation time， ICU stay， infectious markers [C-reactive protein （CRP）， procalcitonin （PCT）， interleukin-6 （IL-6）， white blood cell count （WBC）， and neutrophil percentage （N%）]， Acute Physiology and Chronic Health Evaluation Ⅱ （APACHE Ⅱ） scores， and total incidence of adverse reactions were compared between two groups of patients. At the same time， subgroup analysis was conducted based on the severity of the condition， mechanical ventilation status， and baseline renal function. RESULTS The 28-day mortality rate of patients in the combination group was significantly lower than that in the control group （20.6% vs. 34.6%， P＝0.022）， and the clinical effective rate was significantly higher than that in the control group （80.1% vs. 65.4%， P＝0.004）. The mechanical ventilation time and ICU hospitalization time in the combination group were significantly shorter than those in the control group （[ 7.2±2.4） days vs. （10.4±3.6） days， （10.5±3.1） days vs. （13.7±3.8） days； P＜0.01].After 7 days of treatment， the CRP， PCT， IL-6， WBC， N% and APACHE Ⅱ scores of patients in the combination group significantly decreased compared to before treatment， and the decrease was significantly greater than that of the control group （P＜0.01）. There was no statistically significant difference in the total incidence of adverse reactions between the two groups of patients （11.8% vs. 13.5%， P＝0.690）. Subgroup analysis showed that among high-risk （APACHE Ⅱ score≥15） and mechanically ventilated patients， the 28-day mortality rate and weaning time of the combination group were significantly lower/ shorter than those of the control group （P＜0.05）， while there was no significant difference in the total incidence of adverse reactions between the combination group and the control group after dose adjustment in patients with chronic renal insufficiency （P＞0.05）. CONCLUSIONS The CAZ/AVI combined with AMK regimen has better anti-infective efficacy and good safety in patients with severe pneumonia caused by CRE infection compared to the CAZ/AVI regimen alone； the survival benefits of this joint regimen are more significant in high-risk and mechanically ventilated patients， with critically ill patients being the main beneficiaries.