A wireless network access device for positioning a mobile device includes a distance acquiring module, an information receiving module and a position determining module. The distance acquiring module acquires an initial distance between the wireless network access device and the mobile device in an initial position and an intermediate distance between the wireless network access device and the mobile device in an intermediate position. The information receiving module receives a distance, angle and orientation of movement of the mobile device from the initial position to the intermediate position. The position determining module determines a current position of the mobile device according to the received distance, angle and orientation of the mobile device, the initial distance and the intermediate distance.