Introduction <p>Subsyndromal delirium is characterized by one or more features of consciousness disorders, decreased attention, and changes in cognitive function, which is associated with an increased risk of poor prognosis. However, studies on postoperative subsyndromal delirium in patients undergoing brain tumor surgery are lacking. This study aimed to investigate the influencing factors of subsyndromal delirium in patients undergoing brain tumor surgery and to construct a predictive model.</p> Methods <p>Patients were from the Department of Neurosurgery at West China Hospital in Sichuan Province, China. The assessment of postoperative subsyndromal delirium was primarily conducted using the confusion assessment method (CAM). In addition, detailed clinical data of the patients were collected and analyzed.</p> Results <p>A total of 216 patients who underwent brain tumor surgery were included,60 of whom experienced subsyndromal delirium (27.78%). Four risk factors were identified for the development of subsyndromal delirium in patients, including education level, anesthesia duration, postoperative body temperature, and postoperative pain score. The AUC values for our modeling and validation groups were 0.850 and 0.814, respectively, indicating good discriminative ability. Additionally, the AUC for all samples is 0.813, while the Optimism-corrected AUC for 1000 resampling of Bootstrap resampling is 0.812.</p> Conclusions <p>The established prediction model demonstrated good predictive ability. On the basis of these four predictors, patient risk stratification can provide a reference for formulating prevention and intervention measures.</p>