Abstract: Fibroblast activation protein (FAP) is a serine protease with dipeptidyl peptidase and endopeptidase activities, often overexpressed in tumor-associated fibroblasts. Currently, the use of radioisotope-labeled fibroblast activation protein inhibitors (FAPI) PET/CT in tumors has become a new hot spot in nuclear medicine research. However, FAP is also highly expressed in activated fibroblasts, and there has been some progress in the application of FAPI PET/CT in non-tumor diseases (such as myocardial infarction, interstitial pulmonary fibrosis diseases, and immunoglobulin G4-related diseases, etc), holding potential for in the early diagnosis and efficacy evaluation of these diseases. The authors review of the application and research progress of FAPI PET/CT in non-tumor diseases.