The working grounding mode of high-speed electric multiple units（EMU）imposes a significant effect on distribution of grounding reflux. The distribution law of grounding reflux among each carbon brush is of great significance to the lifetime of brush as well as safe and reliable operation of EMU. In this study

to reveal the effect of working grounding mode on grounding reflux

a high-speed EMU grounding reflux model was built with the software Pspice based on real EMU body and its grounding way

effect of working grounding mode on distribution law of grounding reflux was analyzed

and the data obtained from simulation were compared with the data tested on site. The results show that the maxim

um working grounding current reaches 300 A before the improvement of grounding mode

while the working current is reduced by 13%

2

1% of total traction current

and the current difference among carton brushes is reduced to 2% of total traction current after the improvement.Conclusion is drawn that the working current and the difference of working current among carbon brushes can be reduced efficiently by increasing points of working grounding. The conclusion may provide a basis for determining working grounding mode of standard high-speed EMU.