A method of switching mutual repulsive thyristors in the process of on-load tap changer is proposed.Excess current of transformer tap changing winding is limited by controlling the switching of mutual repulsive thyristors at the instantaneous of current passing zero.Theoretical analysis and experimental waveforms show that this method can switch on-load transformer tap fast and smoothly and has no electric arc.This method can also be applied to switch electrical source of inductive load or bring-in spare power supply.