Abstract: Ultra-small superparamagnetic iron oxide(USPIO) particles have been clinically applied in MRI negative contrast in recent years because of the particles high spatial resolution and low toxicity.With the rapid development of molecular imaging and polymer technology, numerous kinds of tumor-targeted MRI negative contrast have been investigated comprehensively.Combining USPIO with different tumor-targeting carriers in the early diagnosis of cancer, assessing the therapeutic effect, and tracing cancer stem cells have great potential and advantages compared with traditional gadolinium chelates MRI contrast.