This study develop an interactive HTML5 optical numerical simulation and explore its applications within optics teaching. The interface design allows students to visually observe the impact of changes in optical parameters on simulation outcomes. We introduce optical simulation exercises featuring random parameters to personalize learning experience. Utilizing the cross-platform capabilities and interactive features of HTML5, this program enables convenient learning and practical activities for students at any time and place. Through three classic optical cases—geometric optical imaging, Young's double-slit interference, and Fresnel circular aperture diffraction as examples, we demonstrate the design philosophy and application value of our HTML5-based optical numerical simulation teaching tool.