Background Blood glucose variability is associated with poor prognosis after cardiac surgery, but the relationship between glucose variability and postoperative delirium in patients with acute aortic dissection is unclear. The aim of this study is to investigate the association of blood glucose variability with postoperative delirium in acute aortic dissection patients. Methods We prospectively analyzed 257 patients including 103 patients with delirium. The patients was categorized into two groups according to whether delirium was present. The outcome measures were postoperative delirium, the length of Intensive Care Unit stay and the duration of hospital stay. Multivariable Cox competing risk survival models was used to assess. Results A total of 257 subjects were enrolled, including 103 patients with delirium. There were statistically significant differences between the two groups in age, body mass index, first admission blood glucose, white blood cell counts, Acute Physiology and Chronic Health Evaluation II score, hypoxemia, mechanical ventilation duration and the length of Intensive Care Unit stay (P < 0.05). The median of mean of blood glucose and standard deviation of blood glucose were higher in the delirium group than in the non-delirium group, and the difference was statistically significant (P < 0.05). In model 1, the adjusted hazard ratio of standard deviation of blood glucose was 1.436 (P < 0.05). In Model 2, the SDBG (AHR = 1.418, 95% CI = 1.195–1.681, P < 0.05) remained significant after adjusting for confounders (P < 0.05). The area under curve of the SDBG ROC was 0.763 (95% CI = 0.704–0.821, P < 0.01). The sensitivity was 81.6%, and the specificity was 57.8%. Conclusions Glucose variability is associated with the risk of delirium in patients after aortic dissection surgery, and high glycemic variability increases the risk of postoperative delirium.