Abstract: In order to study the effect of proton with some energy in different penetration depth on material properties,a non-equilibrium statistical model of proton irradiation process was established based on the randomness of collisions during passing process to get the passing growth rate function and penetration depth probability density function respectively for high energy and low energy proton.Taking the proton irradiated Kapton film as an example, the analysis results show that,the product of the most probable penetration depth of high-energy proton and its corresponding maximum probability density is a fixed value;but with the energy increasing of the low energy proton,the product of the most probable penetration depth of low-energy proton and its corresponding maximum probability density is gradually reduced to a certain value;by contrast, it is found that the energy demarcation line between high energy proton and low energy proton is about 10⁵ eV.