In case of digital products, particularly portable things make negative influences in working in the respect of various limited resources like small-sized display, low resolution, and inconvenient input method, etc. Due to these reasons, the users are recognizably overloaded during coming into and leaving from display screen. For this, display screens of potable digital product are suggested to be changed to user centered G.U.I design, especially design steps and methods are required in relation to inputting data on actual LCD display screens. However, G.U.I(Graphic User Interface) design process differs from each enterprise and designer in practice and there is no settled model in detail. Therefore, thesis is intended at educational level to suggest process models with case studies on G.U.I. design of MP3 players that are digital products not Web design. As a result, totally 8 steps are ideal on the G.U.I design process system of portable MP3 player; Idea development, Rendering, BMP changing and color Table setting, Icon making, coordinates value appointment and setting up design guideline, color correction, and maintenance. Thesis systematizes G.U.I working process which has been difficult for any common denominator and it is applied to digital products G.U.I design as a practical education model. Therefore, thesis anticipates it is to be used as a step-by-step educational guideline. Digital product G.U.I designers having competitive power against new goods are required and university education has enormous charge in the era of digital technology world, so it has to be coordinated mutually according to levels, steps, and program case studies with basic art principle of originality.