A steering power system for an electric vehicle and a method for controlling same are provided. The steering power system includes: a steering motor; a steering motor controller, configured to control the steering motor; a high voltage power battery, configured to output a first voltage; a low voltage storage battery, configured to output a second voltage; a buck DC-DC converter, configured to convert the first voltage into the second voltage for being supplied to the low voltage storage battery when a high voltage system works; and a boost DC-DC converter, configured to convert the second voltage into the first voltage. When the high voltage system has an abnormal power failure, the boost DC-DC converter converts the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller.