Abstract: An electronic system is provided. The electronic system comprises: a processor, a mobile device, a plurality of expansion ports and an expansion device. The mobile device can work as a standalone system, wherein the mobile device comprises a plurality of first function modules. The expansion device comprises a plurality of second function modules, wherein the expansion device connects to the mobile device through the plurality of expansion ports. When the mobile device and the expansion device are connected together to form the electronic device, the first processor controls the electronic system to perform the plurality of first and second function modules.