Abstract: Experimental studies and theoretical analysis on compressive properties of composite laminates with the edge rectangular delamination defect were carried out. The influence of laminate thickness (including stacking sequences), delamination location, shape, area and environment on the compressive strength was discussed. Both the delamination developing model and the soft inclusion model were used to estimate the compressive strength of laminates with delamination and to analyze the failure mechanism. The results show that medium thick laminates and thin laminates are sensitive to the edge delamination defect, while thick laminates are not. The defect location and shape have a certain effect on the laminate compressive strength. The hygrothermal environment not only changes the compressive mechanism of laminates with defect, but also affects the compressive strength of medium and thin laminates. The soft inclusion model is much more effective and can be used in engineering design analysis.