In order to analyze the internal material properties of the isotropic c omposite material,combined with the theory of laser ultrasound,the simulation software Comsol Multiphysics is used to establish an equivalent model of the transversely isotropic materials excited by the laser thermoelastic ultrasonic wave,by setti ng a perfect matching layer,low reflection boundary,etc.The method eliminates the boundary echo.The finite element method is used to simulate the physical proce ss of ultrasonic excitation in transversely isotropic materials,and the time-doma in analysis of the defect echo signal was carried out.The results show that the in crease in the thickness of the plate will gradually transform the ultrasonic wave into a higher-order mode,and as the thickness of the plate increases,the cut-off fr equency of the mode will gradually decrease,and the ultrasonic wave propagating in the isotropic composite material will gradually lose the Lamb wave.In turn,it show s the characteristics of surface waves,transforming Lamb waves into surface waves and excites Rayleigh waves.This simulation lays a foundation for further research o n the generation of ultrasonic waves and defect location in complex media.