Based on a physical model experiment, the wavelet transform theory, and the shear instability theory, temporal and spatial variation characteristics of shear waves were investigated under the conditions that the incident waves were regular waves and the topography was a flat slope. By analyzing the wavelet energy spectrum of the shear wave velocity time history under 15 wave conditions, results can be obtained and show that when the incident waves are regular waves and the topography is a flat slope, shear waves can be observed but the temporal and spatial variations are not significant; the variation of shear waves over time is continuous once it has been generated; shear waves are more dominant in the energy spectrum in the direction along the bank than in the spectrum vertical to the shoreline; an increase in the slope will reduce the generated area of shear waves; and the shear wave frequency, caused by the shear instability, changes around 0. 015 Hz with a gradient of 1∶40 or a gradient of 1∶100.