An analytical model named fibres bend model (FBM) is presented for the in plane mechanical properties of stitched composite laminates. It is supposed that the primary reason of the effect of the in plane mechanical properties of stitched composite laminates is the misalignment of the fibres as they are forced to spread around the stitches. The geometrical characteristics of the fibres in the stitch unit cells are considered. The elastic relation of stress and strain of the stitched laminates is obtained finally. The in plane tensile strength is calculated in the example of the stitched composite laminates [0/45/0/-45/90/45/0/-45] 2S . The results show that the theoretical predicted values accord well with the experiments. The model is proved to be feasible.