The results indicated that age, current smoker, heavy drinker, MMSE score, hypertension, diabetes mellitus, chronic kidney disease, history of stroke, coronary arterial disease, dementia, history of psychiatric illness, ASA physical status III–IV, general anesthesia, anesthesia time, operative time, intraoperative blood loss, blood transfusion, β-blockers, ACEI drugs, use of psychotropic drugs, preoperative CRP level, and preoperative ALB level were significantly associated with postoperative delirium after primary TJA. Here, CRP is linked to delirium.