Delirium is an acute brain dysfunction syndrome that is common in adult critical care patients. The pathogenesis of delirium is highly related with neuroinflammation, neurotransmitter imbalance, abnormal stress response, and cerebral ischemia. In intensive care unit (ICU), the occurrence of delirium is accompanied with long-term cognitive impairment in patients. Effective assessment tools can detect ICU delirium as early as possible, and subsequent treatment can improve the clinical outcome. However, there are no specific protocols for the treatment of ICU delirium, and active prevention is of particular important. This narrative review aims to address the risk factors, pathogenesis, diagnosis, treatment and prevention of ICU delirium, with a view to increase the understanding of ICU delirium and standardize management.