Abstract: Cancer-associated fibroblasts, as a key component of the tumor microenvironment, exhibit significantly high surface expression of fibroblast activation protein (FAP). This differential expression between tumor and normal tissues makes FAP a highly promising target for tumor diagnosis and treatment. New molecular imaging probes based on fibroblast activation protein inhibitors (FAPI) not only demonstrate superior diagnostic efficacy compared to ¹⁸F-fluorodeoxyglucose but also facilitate patients′ prognostic and therapeutic evaluation by quantifying FAP expression. This capability provides guidance for personalized treatment strategies in oncology, while also optimizing radiotherapy target delineation. In radioligand therapy, FAPI probes labeled with therapeutic radionuclides have shown manageable safety profiles and potential for objective disease response in the treatment of refractory tumors, with preliminary clinical evidence supporting their translational potential. The authors review the application progress of FAP-targeted molecular imaging in the diagnosis and treatment of malignant tumors and propose future research directions and potential technical improvements.