The cardiopulmonary bypass technique is a double-edged sword. On the one hand, it helps surgeons to complete cardiac surgery. On the other hand, due to the changes in blood flow mode, low temperature, blockage of small blood vessels by tangible cell debris, and tissue ischemia-reperfusion during cardiopulmonary bypass, many complications are caused, among which acute kidney injury is one of the most common complications. Dexmedetomidine, as an alpha 2 adrenergic receptor agonist, has good sedative, analgesic, and anti-anxiety effects, and has been widely used in clinics. Its perioperative organ protection effect is increasingly prominent. Several studies have found that dexmedetomidine has a good preventive effect on acute kidney injury associated with cardiopulmonary bypass. This article aims to explore the protective effect, possible mechanism and clinical application of dexmedetomidine in cardiopulmonary bypass-induced acute kidney injury.