Numerical model for laser-generated Lamb waves is established based on spectral finite element method and modal expansion method. The dispersion curves and propagation characteristics of laser-generated Lamb wave propagating along different directions are simulated. The simulation results show that phase velocity and group velocity of guided waves in anisotropic plates can be calculated efficiently by using spectral finite element method. And the laser-generated Lamb wave can be simulated in any direction by combining spectral finite element method with the modal expansion method. Furthermore, propagation velocity and dispersion characteristics of Lamb waves in different directions are closely related to the anisotropy of the material. The numerical simulation provides a theoretical basis for better understanding of the propagation of guided wave, the choice of excited signal and the identification of detected signal in the complex media.