Aiming at the displacement measurement problem of two-dimensional high-frequency motion of two-axis piezoelectric shear stacks driven by high-frequency voltage, a method for measuring the displacement of piezoelectric shear stacks by using the machining trajectories of atomic force microscope (AFM) probe in tapping mode was proposed. Firstly, the thermoplastic polymer polymethyl methacrylate (PMMA) film was prepared, and then the AFM probe tapping experiment was carried out. By scanning the processing trajectory of the AFM probe and post-processing it, the two-dimensional high-frequency motion displacement of the piezoelectric shear stack was successfully obtained. Accurate detection of two-dimensional high-frequency complex motion of piezoelectric shear stacks in a semi-contact manner is realized. Based on the experimental data, the variation of the two-dimensional motion displacement of the piezoelectric shear stack with the voltage amplitude and frequency is analyzed.