A network device includes a status displaying module, a network module, a processor, a power providing module, and a power saving circuit. The network module implements network functions of the network device. The status displaying module receives displaying signals from the network module. The processor directs the network module to implement the network functions. The power providing module provides power for the processor, the network module, and the status displaying module. The power saving circuit couples the displaying signals to obtain coupled signals and controls modes of the processor and the power providing module according to presence of the coupled signals.