Graphene structural defects, including vacancies and line defects, are ubiquitous in assembled anti-wear coatings. The most typical line defects, such as atomic step edges and in-plane defects, are particularly susceptible to severe mechanical deformation and stress during tribological tests, which significantly declines load-bearing capacity and durability of graphene coatings. Herein, we utilized chemically inert diamond probes to systematically investigate the wear behavior of graphene step edges and in-plane defects under high contact stress. The experimental results show that at a critical contact stress (∼6.7 GPa), the graphene defects undergo significant mechanical degradation, characterized by pronounced tearing and folding along a direction oriented approximately 60° relative to the step edges and in-plane defects. Interfacial adhesion and friction measurements revealed that the observed purely mechanical wear behavior is governed primarily by the weakened chemical interactions at the contact interface under high mechanical stress. Furthermore, lattice characterization of the fractured edges using conductive atomic force microscopy (CAFM) shows that the torn graphene edges predominantly exhibit a zigzag (ZZ) crystallographic orientation, suggesting that a preferential tearing direction along the ZZ orientation. Further molecular dynamics (MD) simulations confirmed an intrinsic preference for ZZ-direction tearing, irrespective of stretching orientations or defect presence. This study provides insights into the failure mechanisms of graphene coatings subjected to high mechanical stress.