Abstract: Fibrosis is a key pathological process in various diseases. Fibroblast activation protein (FAP) is a membrane protein overexpressed in activated fibroblasts. FAP-positive fibroblasts also play a significant role in non-malignant pathophysiological processes such as wound healing, inflammation, or ischemia. Upregulated FAP expression can be observed in a variety of malignant tumors and benign fibrotic diseases. Radionuclide-labeled fibroblast activation protein inhibitor (FAPI) PET imaging provide a highly sensitive, comprehensive, and non-invasive method for detecting FAP expression, showing great potential in the diagnosis and evaluation of fibrotic diseases. The authors summarize the application of FAPI PET imaging in benign fibrotic diseases of organ, including the heart, kidneys, lungs, and liver, aiming to provide reference for the non-invasive assessment and clinical decision-making in benign fibrotic diseases.