1. A method for express execution of navigation function with a touch-control interface for a computer system, comprising the following steps of: (a) turning on the computer system; wherein the computer system is arranged such that the computer system at least includes a data storage device, a system memory, a BIOS, a touch-control display device, and a position detector; and the data storage device stores a first operating system, a touch-control display device driver for activating the touch-control display device, a position detector for activating the position detector, a navigation program, and a map image file; (b) executing the BIOS of the computer system; (c) before loading and executing the first operating system, performing the steps of: (c1) detecting the touch-control display device and the position detector; (c2) loading and executing the touch-control display device driver to activate the touch-control display device; (c3) displaying an executive item icon representing the navigation function with the touch-control display device; wherein the executive item icon representing the navigation function is for executing a procedure for loading and executing the first operating system, activating the position detector to determine a current position of the computer system, and loading and executing the navigation program to map the current position to the map image file; (c4) detecting whether a selection is made by touching the executive item icon displayed on the touch-control display device; and (c5) executing the procedure corresponding to the executive item icon when the executive item icon representing the navigation function is touched on the touch-control display device.