Taking no-load closing inrush current theory of a single transformer as a foundation, combined with the transformer of the situation in practice, this paper further studies transformer group inrush current. Based on transformer group no-load closing characteristics, it proposes to increase the system impedance and capacitors. Through contrasting the flux changes between the transformer before/after increasing system impedance, it analyzes its impact on the inrush current and describes a method to select the best impedance values. Finally, no-load closing inrush current of transformer group simutaneously switch-on is simulated by using Matlab, and its value is compared with inrush current value of the shcheme of installing single resistor and the scheme of both installing resistor and capacitor. Simulation results show that this suppression scheme effectively suppresses the transformer group inrush current.