针对掺钛铌酸锂ＭａｃｈＺｅｈｎｄｅｒ型波导电光调制器的结构及折射率分布，运用有限差分束传播方法（ＦＤＢＰＭ）进行模拟计算，取得了二维情况下的最佳设计尺寸在此基础上，把所得的设计结果与原有的用快速傅里叶束传播方法（ＦＦＴＢＰＭ）所得的结果进行比较和分析结果显示，运用有限差分束传播方法不仅取得了预期的结果，而且，这种方法比原有的快速傅里叶束传播方法更快捷和方便，是器件设计的理想和现实的数值模拟工具 In view of the structure and refractive index distribution of Mach-Zehnder waveguide electro-optic modulator doped with TiNbO3, finite difference beam propagation method (FD-BPM) is used to simulate the structure and get the best design dimension in two dimensions Based on the comparison of the design results obtained with FFT FFT and FFT FFT, the results show that not only the expected results are obtained by the finite difference beam propagation method, but also , This method is faster and more convenient than the original Fast Fourier Transform method and is an ideal and realistic numerical simulation tool for device design.