An energy management method and system are provided for a receiving terminal of a simultaneous information and energy transfer system. The method comprises the steps of: activating a battery to provide a working power supply, receiving a simultaneous information and energy transfer signal, processing the signal and harvesting energy in the signal, storing the harvested energy into a temporary energy storage unit, and stopping the battery from supplying power, and charging the battery from the energy stored in the temporary energy storage unit. The system comprises a receiver and an energy management module.