Based on the actual situation of CO2 laser beam heating packaging material, a mathematical model of CO2 laser irradiating packaging materials is established. Combining with the actual boundary conditions, the analytical expression of relationship between cutting depth and laser beam parameter is built up by calculus. Experiments are designed to examine the mathematical model. Diagrams of each parameter are drawn using Matlab software. Theoretical analysis and experimental results indicate that the lower speed of laser beam moves and higher power of laser, the deeper the hole will be, and the model has been revised to be in accord with experimental results. The model can be used to predict the capability of low-power laser cutting.