Abstract: Based on the excellent physical and chemical properties such as degradability, low cytotoxicity, imaging performance, photothermal effect and carrier ability of iron oxide nanoparticles, as well as their diverse synthesis methods, their application in tumor diagnosis and treatment has been widely studied. Iron oxide nanoparticles not only show important application value in tumor diagnostic techniques such as nuclear magnetic resonance imaging and computed tomography, but also play a key role in the field of tumor therapy, such as photothermal therapy, photodynamic therapy and drug therapy. Based on these characteristics, this paper will review the properties, synthesis methods and applications in tumor diagnosis and treatment of iron oxide nanoparticles to illustrate the possibility of their clinical application.