The liver is a common site for tumor metastases. Liver metastases often occur secondary to malignancies including colorectal cancer, pancreatic cancer, melanoma, lung cancer, and breast cancer, accounting for nearly 25% of all cancer metastases. The 1-year survival rate for all patients with liver metastases is 15.1%. Early diagnosis and precise treatment are crucial for improving patient prognosis. As an imaging technique that combines functional metabolism with anatomical structure, 18F-FDG PET/CT plays an increasingly important role in the diagnosis, staging, and treatment planning of liver metastases. This article reviews recent advances in 18F-FDG PET/CT research on liver metastases, including its applications in diagnosis, differential diagnosis, pre-treatment evaluation, efficacy assessment, and prognosis prediction; its advantages and disadvantages in comparative imaging; new technological developments such as delayed imaging and image optimization; diagnostic pitfalls in certain diseases; and its role in guiding radiotherapy. Finally, it summarizes the application of artificial intelligence technology in the diagnosis and treatment of liver metastases and provides prospects on the future development directions of 18F-FDG PET/CT in this field.