1. A method for simplifying a menu selection on a cellular phone, wherein an operating system installed in said cellular phone proceeds with a process comprising the steps of: (a) reading a memory of the cellular phone while said cellular phone is turned on; (b) determining whether a topmost sub-menu set instruction with respect to a most frequently used one of a plurality of sub-menus already being set and stored in said memory; (c) if yes, showing said most frequently used sub-menu on a topmost position of a main menu as a topmost sub-menu on a display of said cellular phone.