32To simplify the experimental process, most experiments carried out to make quantitative predictions of environmentally assisted cracking (EAC) growth rate of stainless steel or nickel based alloy are based on standard specimen in a simulated high temperature water environment in laboratories. In the other hand, the mechanical state and geometrical shape of the flaws in the components of light water reactors (LWRs) are usually more complex than the cracks in standard specimens. It is well known that the mechanical factor near to the crack tip is one of the most important factors affecting EAC growth rate in high-temperature aqueous environments. Based on an EAC experiment with a mock-up pipe specimen with two inner axial cracks and a numerical simulation by the elastic-plastic finite element method (EPFEM), it is analyzed that the effect of the different mechanical parameter selection in describing mechanical state close to the tip of EAC on quantitative estimation of EAC growth rate at flaws in nuclear pressure vessels and piping in this study. And the study is expected to form a bridge between predicting EAC growth rate in the stainless steel or nickel based alloy and evaluating EAC growth in key structural components in LWRs.