In teaching experiment, Fresnel diffraction pattern that matches the theory cannot be frenquently and obviously observed due to the limitation of diffracting object processing precision and camera sensitivity. In this paper, VirtualLab Fusion simulation platform is used to calculate and simulate Fresnel diffraction patterns of circular aperture and stop with different sizes and different observing positions. Then the optical experiments, simulation calculations and theoretical predictions are carried out for circular apertures and stops with specific sizes respectively, and then all results are analyzed and compared with each other. It is believed that this will help to enhance teaching effectiveness.