A communication system equipped with a shared antenna includes an antenna, a first communication module, a second communication module, and a switch module. The first communication module processes a first communication signal and transmits the first communication signal to the switch module. The second communication module processes a second communication signal and transmits the second communication signal to the switch module. Additionally, the first communication module controls the switch module to transmit the first communication signal or the second communication signal to the antenna, and the antenna emits the first communication signal or the second communication signal.