Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, and its mortality ranks fourth in global malignant tumors. Early diagnosis of HCC has an important impact on the survival rate of patients. Exosomal microRNA (miRNA) is closely related to the occurrence and development of HCC. It can be secreted and transferred to recipient cells through the corresponding target genes, and play a role of regulating cancer progression. Exosomal miRNAs have great differences in the expression of HCC patients and in vitro cell lines, and it has the advantages of high content, specificity and stability relative to circulating miRNAs. It not only can better distinguish between HCC and healthy patients, but also can be further differentiated from hepatitis or cirrhosis, and it also has certain value in the diagnosis of recurrent HCC.