A method for automatically establishing a wireless network used in a wireless access point (AP) device is provided. The method comprises the steps outlined below. A first virtual AP unit is activated and operated in a provisional station mode according to a default configuration. The AP device determines whether the wireless AP device is connected to an access controller (AC), if the wireless AP device and the AC are connected, the wireless AP device communicates with the AC to perform a configuring process according to a retrieved configuration to activate a second virtual AP unit. The wireless AP device operates the second virtual AP unit in a configured mode and operates the first virtual AP unit in a provisional AP mode.