In Linux system the Input sub-system is character driven system. Now android, X-windows, Qt, and many other applications in Linux system for input devices such as keyboard, mouse, touch screen support all through, or more and more inclined to standard Input subsystem. Based on current conditions, this article first from Input_dev layer, Input Core layer and the Event Handler layer introduced the implementation of Input sub-system framework, and then achieve it through the Input sub-system for 4x4 matrix keypad and the user in the application layer use the interface function provided by Input sub-system to operate the buttons in order to view the specific states and values of keys. The results shows that the keypad driver in Input sub-system are more stable and have a high efficiency and so it has a good common use.