Abstract: The analysis of the shearing stress in bending is an important content in mechanics of materials. However, it is easy to cause the conceptual confusion in demonstrating the existence of shearing stress on adhesive interface of stacked beam by comparing the deformation of the stacked beam and that of the integrated beam. The method based on mechanics of materials is adopted in this study to investigate the effect of the interaction between the two bonded layers, and in essence the constraint to the tension and compression deformation of the two layers is provided by bonding rather than constraint to the shearing deformation between two layers. This constraint to the tension and compression makes a redistribution of the normal stress on the cross section, and results in a significant difference between the bending deformations of the two types of beams. The analysis process can inspire students to explore the mechanical essence behind the experimental phenomena and understand the related mechanical concepts.