Abstract: The guided-wave tomography method based on full-waveform inversion has higher imaging accuracy compared with other tomography algorithms and shows great potential for application in industrial corrosion detection. Currently, the A0 and S0 modes are primarily used for ultrasonic guided wave testing based on full-waveform inversion. Limited by the sensitivity of the selected excitation frequency band, wavelength size, and inversion thickness, the imaging accuracy of A0 and S0 modes is relatively low when used for shallow and small-scale corrosion defect detection. In this paper, a full-waveform inversion method is proposed for high-precision imaging of shallow and small-sized corrosion defects using SH1 mode waves. Firstly, the finite element method is used to simulate the time-domain waveforms collected from a circular array on the surface of aluminum plates containing defects of different sizes. Then, the frequency domain full-waveform inversion algorithm is used to process the simulation data. The imaging accuracy of the full- waveform inversion algorithm on defects of different sizes was compared and analyzed when exciting guided waves of A0, S0, and SH1 modes. Finally, the influence of defect location and complex defects on imaging accuracy is investigated. The imaging results reveal that the SH1 mode provided superior imaging resolution compared to the A0 and S0 modes when the defects are situated at the center of the annular array. Furthermore, the full-waveform inversion algorithm maintains high imaging resolution even when the defects are off-center or irregularly shaped. This validates the feasibility of employing the full-waveform inversion algorithm for imaging shallow surface corrosion defects in SH1 guided waves.