Abstract: A quasi-3D finite element and Virtzual Crack Extension Method of Hellen (1) are used to investigate the energy release rate for delaminated composite with various laminate parameters. The numerical results have shown that this method presents an effective approach ti predict the initistion and propagation mechanism of delamination.Ccrnparing the theoretical results with experimental evidence, it can be seen that for a given angle between the crack front and the fiber orientation of lateral delaminatod layers the eritical energy release rate could be considered as the material behavior for controlling the delamination growth of composite laminate.