Abstract: A novel three-dimensional composite damage model based on continuum damage mechanics (CDM) was developed to investigate low-velocity impact behavior of composite laminates. The maximum strain failure criterion was used to predict the initiation of fiber damage and the fiber damage revolution was evaluated by a bi-linear damage constitutive relation. A physically-based failure theory and three dimensional Puck criterion was employed to capture the onset of matrix damage and the damage evolution was determined by the effective strain on the fracture plane under the particular fracture angle. The in-situ strength of transverse tensile and in-plane shear depended on the assumption of fracture mechanics. The mesh dependency was alleviated effectively by introducing the characteristic length of element in the constitutive model of fiber and matrix damage. The interlaminar delamination damage was simulated by the cohesive element. Quadratic stress criterion and B-K power law was adopted to confirm the damage initiation and damage revolution for the interface element respectively. The impact damage and impact responses of composite laminates under four levels of impact energy were studied by experimental and numerical method. The agreement between the simulation results and experimental results about impact-force curves, delamination shape and size shows that the finite element analysis model can effectively predict the impact responses and impact damage.