This is a study about Graphical User Interface(GUI) and Multi-Model Interface(MMI) interfaces. We try to find out if the factor of age or the design of interfaces would affect the microwave oven interface manipulation by investigating the elder and younger users. We also try to find out the differences between the elder and younger users about satisfaction and comprehension abilities when manipulating the interface. Through the investigation we know that younger users have less problems manipulating both single-formed interface (vision interface) and complex-formed interface (vision, touch, sound etc.). The elderly have obvious differences manipulating between single-formed interface and complex-formed interface. They would have problems with text reading, function identification, and comprehension. The display of interface forms would affect the elderly with physical degeneration. It does more benefit and safety to the elderly when manipulating products if the interfaces are displayed appropriately according to different functions and essentiality.