In order to analyze Lamb wave propagation characteristics, a response calculation method based on a semi-analytical finite element is used to solve the Lamb wave excitation response in a plate instead of the conventional experimental method. Compared with the three-dimensional finite element simulation method, simulating the propagation process of guided wave in waveguide medium, via measuring the response of stimulation, can improve the computational efficiency. The Lamb wave excitation response is derived from the previous system functional model by solving the general homogeneous equation of the Lamb wave in the thin plate based on the principle of spectral superposition. For both response and experimental data, the wavelet transform is used to calculate Lamb waves' group velocities. Experimental results are in good agreement with the data obtained by excitation response calculation method. In addition to that, the modal analysis shows consistency. Moreover, the excitation response calculation method is a versatile approach, which can also be used to simulate the propagation process of the guided wave in any section waveguide medium.