For explaining the SCG behavior of polyethylene, the crack layer theory is applied based on the description of two driving forces: crack and PZ. The relations between the speed of SCG, crack length and elapsed time are the most important characteristics of polyethylene resistance to crack propagation, or long-term brittle fracture. The crack layer model of slow crack growth in polyethylene is designed in such a way that it qualitatively reproduces the main features of the process indicated above and makes it possible to quantitatively match any pattern of step-wise crack growth. In this paper, the behavior of SCG of polyethylene is developed for numerical simulation based on the crack layer theory. Some parametric study and applications are addressed based on the developed simulation program.