Abstract: Finite element is adopted to simulate the process with SH ultrasonic guided-wave method to detect the damage at tank bottom plate, and thinning the unit size and time step of the model can ensure the accuracy of the results. After Matlab's spectrum analysis, ten signals, with frequency of 70 kHz and after modulation of Hanning, are chosen to be excitation signals to use fnite element to simulate zero defect, via defects, cracks and etch pits at tank bottom plate. After analysis of SNR (signal-to-noise ratio) of ultrasonic guided-waves' echo signals, the defect position and geometric features can be accurately located, thus providing a frm theoretical support to the application of SH ultrasonic guided-wave detection technology.