Abstract: In this paper, a polystyrene (PS)-supercritical CO₂ system was used herein as a case example to simulate bubble growth behavior and cooling and solidification. The mathematical model based on the cell model was established to solve momentum equation, mass equation and diffusion equation. The software program of system simulation based on the above mathematical model was compiled with MATLAB language. In the process of simulation, the quantitative relationship between process parameters and microcellular morphology was determined by introducing the relationship between the material properties and the temperature, pressure and CO₂ concentration. The results show that CO₂ concentration has the greatest effect on bubble growth, and the effect of temperature is the least for the PS-CO₂ system. According to the simulation of orthogonal, under different processing conditions, the maximum value of bubble radius is 49.5 μm, the minimum value is 1.27 μm, and the suitable bubble radius for microcellular foaming is between 10 μm and 25 μm. In addition, the study of the bubble cooling shows that the increase of cooling rate will increase the bubble density and reduce the bubble size.