A wireless communication system of a notebook computer includes a first antenna, an antenna array module and a wireless local area network (WLAN) module. The antenna array module includes a plurality of second antennas and a plurality of connectors electrically connected to the second antennas via corresponding signal transmission lines, wherein the distance between two adjacent second antennas is identical, and the length of each signal transmission line is equal. The wireless local area network (WLAN) module has a switch unit electrically connected to the first antenna and the antenna array module to select one of the first antenna and the antenna array module to receive/transmit a signal according to an operational mode of the WLAN module.