Numerical simulation and experimental study of the Vickers indentation testing of the Al2O3 ceramic coated by diamond-like carbon (DLC) layer were conducted.The numerical analysis was implemented by a two-dimensional finite element (FE) axis symmetry model.FE analysis results gave insight into the fracture mechanism of DLC films coated on brittle ceramic (Al2O3) substrates.The maximum principal stress field was used to locate the most expected area for crack formation and propagation during the Vickers indentation testing.The results show that the median crack initiates in the interface under indenter,before ring crack occurs as the indenter presses down.Finally,the plastic deformation appears when the indenter penetrates into the substrate.The thicker DLC coating increases the Vickers hardness and fracture toughness.