The utility model discloses a single -phase power supply device, electric Railway traction power supply system, power supply system is including power supply synchronising controller, a plurality of single -phase power supply devices, a plurality of interval interconnection switch, the single -phase power supply device includes many pairs of limit winding transformers, a plurality of power converting cell cubes and main control unit, power supply synchronising controller is responsible for pulling the virtual value of net the whole network voltage, frequency and phase place homogeneous are sent, the single -phase power supply device realizes according to synchronous instruction that three phase current turns into synchronous single phase power, interval interconnection switch connects for unified whole between each service area. The utility model discloses effectively solve the electric energy quality problems that traditional traction power supply system caused to public power grid, for electrified locomotive provides controllable, reliable, continuous power supply, provide the ice -melt function simultaneously, ensured traction power supply system's safe and reliable.