Objective To collect the clinical data of patients in anesthesia intensive care unit (AICU), and analyze the reasons and prognosis of perioperative patient admission to AICU, in order to provide reference for establishment of new AICU. Methods A total of 4 810 patients who were admitted to the AICU of the First Affiliated Hospital of Zhengzhou University from April 1, 2019 to October 31, 2022 were selected and their clinical data were retrospectively analyzed. Their general information ［age, gender, basic disease types, Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) scores］, the cause to transfer to AICU, surgery types, treatment duration of AICU, prognosis [including recovery, transferred to other intensive care unit (ICU), discharged automatically and died], and the reasons for readmission to the ICU (including AICU and other ICU) within 48 h were documented. Results A total of 4 810 patients were admitted to AICU, with an average age of (59±17) years, including 3 085 men and 1 725 women. The median treatment duration was 1 (1) d. Notably, 94.9% (4 563/4 810) of patients returned to the general ward or were discharged after recovery, 0.9% (44/4 810) of patients were transferred to other ICU, 3.5% (170/4 810) were discharged automatically, and 0.7% (33/4 810) of patients died. Patient admissions to AICU originated from three main sources: postoperative transfers (87.2%), ward transfers (10.7%), and emergency admissions (2.1%). Ager surgery, 4 197 patients were transferred to AICU, accounting for 87.2% of the total number. The treatment improvement rate was 97.3% (4 085/4 197) and a median treatment duration in AICU was 1 (1) d. The top six surgical types for postoperative transfers were ophthalmic and otorhinolaryngologic surgery (18.5%), general abdominal surgery (18.2%), urological surgery (14.0%), orthopedic surgery (13.0%), thoracic surgery (11.0%), and oral surgery (8.6%). The primary reasons for postoperative transfers to AICU were surgical factors (29.6%), airway problems (25.5%), and medical complications (24.1%). Among postoperative patients, the readmission rate to the AICU within 48 h was 1.6% (66/4 197), with respiratory complications being the most frequent reason. The readmission ICU mortality rate was 18.2% (12/66). Ward transfers accounted for 513 cases, with a treatment improvement rate of 79.2%. In AICU, the median treatment duration was 2 (4) d for ward transfer patients. The leading reasons for ward transfers to AICU were respiratory disorders (36.1%), circulatory disorders (22.0%), and sudden comatose states (20.3%). Additionally, we recorded 100 cases of emergency admissions, with a treatment improvement rate of 72.0% and a median treatment duration of 6 (9) d. Conclusions Postoperative patients are the main source of AICU patients, with relatively short treatment duration and high improvement rate. AICU plays an important role in the treatment of perioperative patients.