Focal nodular hyperplasia of the liver (FNH) is a common benign hepatic lesion, a concept first proposed by Edmondson in 1958 and adopted by the World Health Organization in 1975.The incidence of FNH is second only to that of hepatic hemangiomas, with a detection rate of 0.8% in adult autopsy reports, and a prevalence of 0.6% to 3.0% in the general population. FNH is a proliferative response of the hepatic parenchyma to vascular malformations, is a non-neoplastic proliferation, and has no malignant tendency. The specific pathogenesis is unclear, and the main etiologic factors proposed include congenital vascular malformations, long-term use of oral contraceptives, pharmacologic liver injury, and smoking. Although FNH can occur at any age, the age of onset is commonly 20-50 years old. Foreign literature reports a higher incidence in women, but domestic reports show similar incidence in men and women, even more male patients. In men, the age of onset is higher, and the size of the lesion is smaller, which is more often manifested as atypical FNH. FNH usually does not cause clinical symptoms, and most of the patients are found during physical examination or incidentally discovered during examination for other diseases, and a few patients have abdominal distension and other discomforts due to the large size of the lesion, such as pain in the right epigastric region or compression of the neighboring organs, and rupture and bleeding are very rare. Since FNH is a non-neoplastic lesion that lacks specific diagnostic markers and does not cause obvious liver function abnormalities, diagnosis mainly relies on imaging tests. Most of the patients were detected by ultrasonography, and the typical ultrasonographic findings were: well-defined isoechoic nodules with rich blood supply, arterial blood flow signals dispersing in a spoke-like pattern from the center to the surroundings, and high arterial blood flow velocity with low resistance. However, due to the poor specificity of the ultrasound manifestation of FNH, the clinical diagnosis rate is low because of the high demand on the sonographer’s personal experience. Enhanced CT and MRI of the abdomen are important examinations for the clinical diagnosis of FNH, characterized by scarring in the central part of the lesion on plain scanning, “fast-in-slow-out” enhancement on enhanced scanning, and delayed enhancement of the central scar. A small number of lesions lack the above typical imaging manifestations and are not easily distinguished from adenomas or even hepatocellular carcinomas. Compared with enhanced CT, MRI scanning is more likely to show central scarring, and the use of liver-specific contrast can further improve the diagnostic specificity and sensitivity. Since FNH is a benign disease and rarely causes clinical symptoms, and even has been reported to disappear on its own, it is recommended to adopt clinical follow-up and regular review. However, the size and number of FNH may progress, and there are even reports of early hepatocellular carcinoma found in the periphery of resected FNH lesions. Therefore, for lesions with atypical imaging manifestations but tending to be benign, review after 3 months may be considered. Surgical intervention should be considered when imaging changes, lesion enlargement, or symptoms occur during the observation period. The more recognized indications for surgical intervention include: large lesions with significant symptoms; atypical imaging manifestations that do not exclude adenomas or hepatocellular carcinomas, etc.; and more significant lesion growth. In conclusion, FNH is a common benign disease of the liver of unknown etiology, which can occur in both sexes and is more common in patients aged 20 to 50 years. Patients are mostly found during physical examination, and MRI is the preferred diagnostic imaging method. Clinical observation is preferred for patients without obvious symptoms and with typical imaging manifestations; surgical resection should be performed for lesions with atypical imaging manifestations, large size and obvious symptoms or rapid growth.