With the development of medical imaging technology, hemodynamics-based functional magnetic resonance imaging (fMRI) has gradually become one of the major tools to investigate human brain function, however, it is of limited temporal resolution. In recent years, neuronal current MRI (nc-MRI) was proposed as a new imaging method to directly map the magnetic field change caused by neural activities. Theoretically, nc-MRI can non-inva- sively locate brain activities with very high spatial and temporal resolution, thus it may greatly improve the study of human brain function. This paper reviews the construction mechanism of nc-MRI, including theoretical model of the neuronal magnetic field and signal source. Arithmetic simulation of nc-MRI signal with an illustration of our work on simulation of a dendrite branch magnetic field is presented. New development of the experimental studies and foreground of nc-MRI area are discussed.