Abstract: Computer simulation of the low-velocity impact process of the composite laminate with prefabricateddefect was performed to demonst rate the impact process and damage progress in detail. A finite element programwritten in FORTRAN was developed to analyze the t ransient dynamic response of composite plates. The Hertziancontact law was modified in order to accommodate the serious damage in the plate. The Wilson-scheme was adoptedto perform time integration for the motion equations of the impactor and composite plate system. The Lagrange multiplier method was used to deal with dynamic contact problems. The result s of computer simulation including theforce history and delamination areas were found to correlate well with the experiment s. The experiment and calculationresults show that the delamination defects in the laminates have the effect that prevents the propagation of delamination.