Liver is the biggest and the most important metabolic organ in human body. Hepatic ischemia⁃ reperfusion injury，fatty liver，cirrhosis，hepatic fibrosis，hepatic peroxidation injury and hepatic drug injury are common liver injury diseases. Stem cells are cells with the potential to self⁃renew and develop into many different cell types. Liver stem cells can be divided into hepatogenic stem cells and extrahepatic stem cells. In the treatment of liver injury，stem cells can repair liver injury through stem cells homing，transdifferentiation and direct differen⁃ tiation，paracrine effect，immune regulation，exosomes and other mechanisms. In the clinical treatment of liver injury，stem cells can play a role directly or indirectly through exosomes indirectly. In addition to repairing liver injury，stem cells⁃derived exosomes can also be used as molecular biomarkers for liver disease diagnosis and prog⁃ nosis monitoring and to assess the toxicity of drugs as well as adverse drug reactions.