Objective To investigate the influencing factors of hypothermia in patients under general anesthesia in the post-anesthesia care unit (PACU) and construct a nomogram prediction model. Methods A retrospective analysis was performed on the clinical data of 261 patients undergoing general anesthesia. The patients were randomly divided into a training set (n=186) and a validation set (n=75) according to the ratio of approximately 7∶3. According to the occurrence of hypothermia in the PACU, the training set was further categorized into a hypothermia group (n=69) and a non-hypothermia group (n=117). Multivariate Logistic regression analysis was used to identify the influencing factors for hypothermia, and a nomogram prediction model was constructed based on these factors. The discrimination and calibration of the model were evaluated using receiver operating characteristic (ROC) curves and calibration curves. Results Of 261 patients undergoing general anesthesia surgery, 118 developed hypothermia in the PACU, with an incidence rate of 45.2%. In the training set, statistically significant differences were observed between the hypothermia group and the non-hypothermia group in age, American Society of Anesthesiologists (ASA) classification, body mass index (BMI), operation duration, intraoperative blood loss, intraoperative fluid infusion volume, intraoperative blood transfusion, intraoperative hypothermia, and intraoperative irrigation (P<0.05). Multivariate Logistic regression analysis showed that age, intraoperative hypothermia, and BMI were influencing factors for hypothermia in the PACU among patients undergoing general anesthesia (P<0.05). The nomogram prediction model constructed based on the above influencing factors achieved an area under the ROC curve of 0.840 (95%CI: 0.780, 0.900) in the training set, with a sensitivity of 78.32% and a specificity of 80.34%, respectively. In the validation set, the area under the ROC curve was 0.727 (95%CI: 0.608, 0.847), with a sensitivity of 72.14% and a specificity of 71.87%, respectively. Calibration curve analysis showed a Brier score of 0.153 in the training set and 0.201 in the validation set. The Hosmer-Lemeshow test indicated no statistically significant difference between the predicted probability and the observed probability of hypothermia (P>0.05). Conclusion Age, intraoperative hypothermia, and BMI are influencing factors for hypothermia occurring in the PACU in patients undergoing general anesthesia. The nomogram prediction model constructed based on these factors shows favorable predictive performance, which can provide a reference for the early identification of high-risk patients and the formulation of targeted temperature protection strategies in clinical practice.