Abstract ： Research purposes ： Some domestic cities are building and will build medium and Fw speed maglev transportation project， the power supply system is an important part of medium and low speed maglev project， DC traction power supply system is concerned with the safety and reliability of maglev traffic operation. This paper tries to understand and master the difference from conventional rail transit power supply system， proposes the grounding protection scheme of traction power supplysystem for medium and low speed maglev traffic，which has great help for the construction of medium and low speed maglev project. Research conclusions ：( 1 ) The power supply system structures in the low - speed maglev and urban rail transit are basically the same. (2) The main difference of maglev transportation power supply system is lies in the contact rail type，reflux，stray current protection，and so on. (3) Taking Changsiia maglev project design as the basis，the setting principle and main performance of magnetic power supply DC system grounding protection are discussed，the relationship of traditional frame work protection and DC grounding protection is analyzed，and DC grounding protection configuration scheme suitable for in maglev transportation is proposed. (4) The research results can be applied for the research and construction of the middle and low speed maglev project.