Background: There is a discrepancy between off-center crack and center-crack.Purpose: Crack grow rule and path need to be investigated under different load conditions.Methods: 3D elastic finite element method is used to create an off-center inner-surface crack model based on Paris-law crack grow equation by ABAQUS.Results: Crack grow rule and path are obtained under different load conditions.The influence of the crack rotation angle to crack extension has been researched.At the same time

centered circumferential crack model has been compared with off-centered circumferential crack model

and the discrepancy has been found.Conclusions: In LBB analysis

off-center influence should be considered in crack leakage analysis

but not necessary in crack stability analysis.