Abstract: To larger grounding circulation current (GCC) produced by 750kV transformer neutral Π type grounding, GCC mathematical model is fabricated, its GCC value and factors are analyzed. Real GCC is measured, its relation is built to load current, and so GCC suppression measure is put forward. Real resistance parameters is used to analyze the GCC change before and after modification, and it is found that GCC is eliminated and consistent with real measured result. The correct theoretical analysis and valid suppression measure are fully tested with related to the GCC of 750kV transformer neutralΠtype grounding.