A communication system includes a microprocessor, a WiFi device, a WiMAX device, common antennas, and switching devices. The common antennas are for receiving a WiFi signal and a WiMAX signal. Each of the switching devices has an input terminal coupled to the corresponding common antenna, a first output terminal coupled to the WiFi device and a second output terminal coupled to the WiMAX device. When the communication system is applied to a WiFi system, the microprocessor controls the switching devices to isolate the WiMAX signal and transmit the WiFi signal via the first output terminals to the WiFi device; when the communication system is applied to a WiMAX system, the microprocessor controls the switching devices to isolate the WiFi signal and transmit the WiMAX signal via the second output terminals to the WiMAX device.