ABSTRACT: This paper presents the implementation of a Graphic User Interface (GUI) for Discontinues Deformation Analysis (DDA). The motivation is to provide a user friendly software for releasing burden of preparing the ASCII input files in original DDA codes. A shell concept is adopted in the design of the GUI. It guarantees the independent between the GUI and original DDA codes. It can also fully utilize the merits of both GUI based modelling approach and ASCII input files based approach. The new developed GUI and some of its functionalities, e.g., directly input data files from ANSYS and UDEC and post processing, are introduced. Finally, two case studies, Brazilian test and slope stability under earthquake, are presented to show some application of the GUI.