Abstract: A 3D visualization system for mineral deposits is an important means to understand the spatial distribution of mineral grades, and a fundamental tool for computer-aided design and planning of mines. Some 3D visualization techniques for modeling mineral deposits were presented and a framework for building a 3D visual modeling system of mineral deposits was proposed. Based on Windows, VC⁺⁺ IDE and OpenGL, a prototype 3D visualization system for modeling mineral deposits was developed. Real data from a Chinese underground iron mine were used to verify the system prototype and the resulting 3D images of boreholes and orebodies were satisfactory, depicting a simulated true picture of the mineral deposit, which demonstrated the effective and efficiency of the visualization system.