Abstract:The finite element analysis software has been widely used in engineering design and scientific research. Being able to observe model conveniently and reflect new theory and achievement are two important factors to judge whether the software is successful. These two factors are correlative with visualization,so visualization is indispensable of the finite element analysis software. The authors make a comparison between GDI and OpenGL which are both popular in graphics system at present;and reveal superiorities of the latter such as extra high speed,powerful drawing function,convenient selection and feedback,nice visual effect,etc. in designing 3D finite element graphics system. How to use OpenGL API and object-oriented programming method to organize complicated data from the 3D finite element graphics system of underground structure is introduced too,and the basic program frame and arithmetic are presented. The authors also introduce how to operate 3D finite element model interactively,how to select node and element quickly,how to draw nephogram and isogram,etc.. Some engineering examples are given.