Delirium is an acute, transient, usually reversible, fluctuating disturbance in consciousness, attention, cognition, and perception. Delirium after cardiac operations is associated with increased morbidity, reduced cognitive functioning, increased short-term and long-term mortality, longer hospitalization and higher hospitalization cost. The diagnosis, prevention and treatment of delirium are of great importance for perioperative care of patients undergoing cardiac surgery. Effective delirium screening tools are very helpful for the recognition and monitoring of delirium after cardiac surgery. In recent years, there has been many new strategies for the treatment, nursing care and prevention of delirium after cardiac surgery. This review focuses on the incidence, risk factors, diagnostic methods, treatment and preventive strategies of delirium after cardiac surgery.