在三维射线追踪中，一般都必须同时考虑引起壳幔结构非均匀性的介质及构造因素．本研究用类似于计算机辅助设计中图形产生的方法，生成三维结构模型．在Ｃｅｒｖｅｎｙ等三维复杂结构中全射线追踪算法的基础上，提出一种在三维横向非均匀结构中进行两点射线追踪的分步搜索法，并给出了数值计算实例． In 3D ray tracing, the media and structural factors that cause the heterogeneity of the crust and mantle structure must all be considered at the same time. In this study, a three-dimensional structural model was generated using a method similar to that used in computer aided design. Based on the full ray tracing algorithm of three dimensional complex structure such as Cerveny, a step search method of two-point ray tracing in three-dimensional transverse non-uniform structure is proposed and a numerical example is given.