The laser rate equation is the core theory that describes the evolution of particle numbers and the interaction with the light field during the laser generation process. However, its abstract mathematical form and complex physical process pose many challenges for teaching. Taking the four-level system as the research object, this paper constructs a visual teaching platform for the laser rate equation based on Matlab numerical simulation technology. It systematically elaborates on the theory of the four-level rate equation and the gain coefficient. Through dynamic simulation, it analyzes the effects of key parameters such as pump power, upper laser level lifetime, and output mirror reflectivity on the particle number density of each level, the gain coefficient, and the output light intensity. Teaching practice shows that this visualization method can concretize the abstract theory, help students intuitively understand the physical meaning of parameter changes, and significantly improve learning outcomes.