Abstract: The modeⅠfracture toughness of Z-pin reinforced double cantilever beam configuration laminates was studied based on mesomechanics and virtual crack closure technique (VCCT). A finite element model was built using solid elements to model the composite laminates and non-linear combined elements to simulate the Z -pin reinforcement. The numerical results of the strain energy release rate were compared between the fracture toughness of the modeⅠcomposite laminate reinforced with the Z-pin and that of the modeⅠcomposite laminate without the Z-pin. The study demonst rates that Z-pin reinforcement can increase the composite delaminated resistance and reinforce the fracture toughness of the modeⅠcomposite laminate aggressively. The influence of design parameters such as the number of Z-pin in the bridging area，the Z-pin density and some other parameters on the toughness enhancement of Z-pinned laminates was investigated.