A power supply system, an electronic device and an electricity distribution method, which can enhance, with maximum efficiency, power distribution of the electronic device. The power supply system includes a power source unit, an electricity distribution unit connected to the power source unit, a system load power supply unit connected to the electricity distribution unit, and a peripheral power supply unit connected to the electricity distribution unit. The electricity distribution unit includes a power consumption prediction module configured to detect system load power consumption and calculate a variation trend of the system load power consumption and a power consumption control module configured to adjust power supply capacities of the system load power supply unit and the peripheral power supply unit according to the variation trend of the system load power consumption.