提出了一种十分有效的提取导波结构传播特性的数值方法 .它的基本思想是把Krylov子空间的模式缩减技术 (Pad啨逼近 /Lanczos分解 )使用在紧凑格式频域有限差分法上 .它把大的系统矩阵降阶为很小的系统矩阵 ,从而加速了矩阵的运算求解 .通过对几种导波结构的分析及和其他方法的比较 ,证明了这种新方法的准确性和高效性 . A very effective numerical method for extracting propagation characteristics of guided wave structures is proposed.The basic idea of ​​this method is to use the mode reduction technique (Pad 啨 approximation / Lanczos decomposition) of Krylov subspace in compact format frequency domain finite difference method The large system matrix is ​​reduced to a very small system matrix, which accelerates the calculation of the matrix. The analysis of several guided wave structures and comparison with other methods prove that the new method is accurate and efficient .