Abstract: Fibroblast activation protein (FAP) is overexpressed in cancer-associated fibroblasts in 90% of epithelial tumors, but hardly expressed in normal tissues. Therefore, FAP is an important target for tumor diagnosis and treatment. A series of imaging agents targeting FAP have shown favorable imaging results in preclinical studies with specific high uptake and non-targeted low uptake. Compared with fluorodeoxyglucose imaging, FAP imaging showed higher uptake value and sensitivity in most malignancies. Since then, a large number of clinical studies have been gradually carried out. Some progress has been made in the study of various malignant tumors with imaging agents targeting FAP, and some studies have confirmed that FAP is effective in some non-tumor diseases (such as myocardial infarction, immunoglobulin G4, Tuberculosis, etc.) are also highly expressed. So imaging agents targeting FAP can also be used for the diagnosis of non-neoplastic diseases. This article reviews the research progress of novel molecular probes for PET targeting FAP and their clinical translation.