Abstract: The concept of cancer diagnosis and treatment has undergone a transition from experience-based medicine to evidence-based medicine and is currently taking steps into the stage of precision medicine. Precision diagnosis is an important basis for clinical treatment schemes and formulation of individual therapies and is the premise of precision therapies. However, because of spatial and temporal heterogeneity of tumors, accurate diagnosis is difficult and therefore improvements in the efficiency of precision medicine in cancer therapies are restricted. Molecular imaging can qualitatively and quantitatively detect key targets in tumors at the molecular level while featuring comprehensive anatomical and morphological details. Thus, it can reveal the biological behavior of tumors more intuitively and comprehensively to provide scientific evidence for cancer precision diagnosis and guide immunotherapies and targeted therapies in cancer treatment. In addition, molecular imaging can facilitate the precise treatment of tumors by using multifunctional molecular probe platforms loaded with therapeutic radionuclides or by labelling with diagnosis-therapy dual-functional radionuclides. Thus, molecular imaging-based precision medicine plays an important role in the fields of basic research, translational medicine, and health medicine, currently and in the future. With the rapid development of molecular imaging techniques, molecular imaging has stepped into the critical stage of clinical translation from the laboratory. In the field, radionuclide molecular imaging leads the cutting-edge technology in translational application owing to its unique superiority, thereby further advancing molecular imaging in cancer precision medicine. This review mainly discusses the significant impact and value of radionuclide molecular imaging in clinical precision diagnosis to provide latest technical information and research ideas for physicians and researchers devoted to cancer research.