A power management system includes a plurality of electronic devices, a power distribution unit, a power management unit and a power control unit. The power distribution unit is connected with the electronic devices for providing electricity to the electronic devices. The power management unit is connected to a network and the electronic devices, so that the electronic devices are connected with the network through the power management unit. The power control unit is connected with the power management unit through the network. The power control unit is configured for controlling the power management unit, thereby sequentially starting the electronic devices.