Susceptibility weighted imaging (SWI) is a magnetic resonance technology with a high resolution, three-dimensional gradient echo and fully velocity compensated sequence. It is also sensitive to substance with different magnetisability. Based on the quantitative reconstruction of SWI, quantitative susceptibility mapping (QSM) has been used in monitoring the change of intravenous iron, calcium, microbleeds and oxygen content. This article summarizes principle of QSM and the latest progress of QSM application in the diseases of central nervous system.