提出一种在OpenGL环境中用四边形近似的方法构造城市轨道交通地下结构三维模型的算法，着重对三维造型中的坐标变换问题进行探讨，并通过实例对提出的算法进行验证。实践证明，所提出的方法可以在OpenGL环境中高效便捷地实现地下结构的三维可视化，能够满足在城市轨道交通三维可视化选线系统中的应用要求。

This paper presents an algorithm by using quadrilateral approximation to model the underground stru - ctures of urban rail transit by software OpenGL． The technique of coordinate transformation in OpenGL was adopted and the availability of the algorithm was verified by an example． The algorithm can be used to model the underground structures efficiently and rapidly and can meet the requirements of the 3D visualization system for urban rail transit line design．