The CNC system is an important accessory for large-scale CNC gantry milling machining. Operators operate the CNC system through the user interface, thereby controlling the large-scale CNC gantry milling to process the workpiece. Due to different user requirements for interfaces, the workload of developing user interfaces is enormous. User interfaces have become one of the most difficult parts in computer software development. The emergence of graphical user interfaces greatly facilitates the use of non professional users. People can operate through windows and menus, facilitating blueprint programming and rapid programming, three-dimensional color dynamic graphic display, graphic simulation, graphic dynamic tracking and simulation, The implementation of zoom functions for views in different directions and local display scales. With the updating and upgrading of CNC systems, as well as the upgrading of user interface aesthetics, the functionality of large-scale CNC gantry milling processing will be further developed in the future.