This paper studies the visualization structural design of lock-head 3D design, aiming at solving the problem of insufficiency of 3D design visual effect of domestic locks. A 3D model design system is developed by C++ object oriented features combined with AutoCAD object ARX development tools, which realizes lock-head 3D model algorithm, lock-head stability checking algorithm, and output of structure stability calculation results. It is proved by the engineering example that the result is intuitive, and helps well the lock-head structural design. It is useful for the 3D visualization technology of the hydraulic structure.