Abstract: The dispersion curve is an important basis for the guided wave testing. The numerical method is popular to calculate the dispersion curves of the special waveguide. But some waveguides with the complex structure can not to be calculated by numerical method. This paper studies on the dispersion curve obtained method from the testing signals. The maximum energy of the signal is applied to manual and automatic access to the dispersion curve based on the time-frequency analysis result. The dispersion curves obtained from the testing signals of the bars and pipes(regular waveguides) are in accordance with the theoretical results. And the method is used to obtain the dispersion curve of the pre-stressed steel strand(irregular waveguide).