Abstract: A model for determining the effective elastic constants of stitched lamina is established, in which the effects of stitching parameters on elastic constants of stitched lamina are analyzed by considering the nonuniform distribution and in-plan waviness of fibers induced by stitching. The results show that, when the stitching direction is perpendicular to the fiber direction, the longitudinal modulus decreases but transverse modulus and shear modulus increase gradually with decreasing row spacing or increasing stitch thread radius.