Abstract: In recent years, radionuclide-labeled drugs targeting fibroblast activation protein (FAP) for tumor diagnosis and treatment have developed rapidly. These drugs generally have relatively conserved structures, but even small structural changes can affect their pharmacokinetic properties and biological functions. The design and development of small-molecule FAP inhibitors share certain common features. By summarizing these design and development ideas, this article aims to provide some reference for the subsequent research and development of radionuclide-labeled fibroblast activation protein inhibitors and other related nuclear drugs.