Abstract: The simplified models of the AFM (atomic force microscope) probe are proposed for a qualitative analysis of dynamic characteristics of the AFM. The forced vibration of the probe is analyzed on the basis of the simplified models. The motion equations are derived based on the models and the wave modes of the AFM probe are obtained by a theoretical calculation. The symmetry problem and the frequency drift are confirmed in the calculation, as consistent with the AFM tests. Meanwhile, an intermittent collision phenomenon is found in the simplified models. The effect of the long-range attractive force on the AFM probe is simulated through a negative spring model.