The present invention provides a network system supporting a plurality of physical layers and the method thereof. The driver system and the method thereof utilizes the basic input/output system of the computer system to setup the network physical layer that is physically connected, and to calculate the simulation device code corresponding to the selected network physical layer according to the setup and the device code read from the network interface adapter, so that the computer system is able to recognize and enable the appropriate device driver of the physical layer. Therefore, the user is able to change the physical layer that is physically connected without reloading the device driver corresponding to the physical layer that is physically connected again and again, and also doesn't have to reconfigure the communication protocol parameters.