Postoperative delirium (POD) seriously affects the outcome of surgical patients after surgery and even affects the long‑term prognosis. At present, the patho‑physiological process of POD is not straightforward. Studying the risk factors of POD can help reveal the pathophysiological mechanism of POD, identify high‑risk patients early, and take effective interventions to prevent POD. Some studies have shown that preoperative blood markers can be used as indicators to predict POD. This review summarized the research on preoperative blood markers to predict the occurrence of POD from six aspects: inflammatory mediators, cholinergic‑related factors, nerve injury markers, hormones and related substances, vitamin D, and gene expression regulation factors. Our review provides a basis for identifying POD high‑risk groups and POD prevention and treatment.