A wireless access point (WAP) includes a radio frequency (RF) module, an identifying module, and a controlling module. The RF module is configured for sending and receiving a wireless signal. The identifying module is configured for identifying whether or not the wireless signal matches the frame format of the PCLP sub-layer of the IEEE 802.11 standards, thereby generating an identifying result. The controlling module is configured for controlling the WAP to switch itself to a power-saving mode (PSM) or a constantly awake mode (CAM), according to the identifying result from the identifying module, wherein in the PSM, under the control of the controlling module, the WAP only receives the wireless signal.