Abstract: Diffraction, as a classic optical phenomenon, is widely present in practical engineering. Therefore, diffraction is a fundamental and difficult knowledge in the daily teaching of optical engineering in universities. However, in the actual teaching process, limited by class hours and experimental conditions, these knowledge point that should be learned mainly focus on typical basic diffraction situations such as single slits, double slits, and circular holes. The diffraction characteristics of complex structures are not introduced in the classes. With the application of various computer programming software in the teaching process, such optical propagation simulation and characteristic analysis can be conveniently realized. This article observes the diffraction pattern and light field distribution of a circular aperture through diffraction simulation, and investigates the influence of changing the size of the annular gap and different shaped apertures on the diffraction results. The results show that MATLAB software has advantages in optical teaching, such as simple operation, unrestricted experimental conditions, and clear phenomenon display, providing a convenient means for computer-aided optical teaching.