Abstract: A multi-scale coupled numerical model was developed to investigate the mechanical behaviors of 3D woven composite pipes. Micro-and meso-scale unit cells were built to represent the inhomogeneity of fiber tow and weave structure of a 3D woven composite pipe, respectively. The periodic boundary condition of the camber shape meso-scale unit cell was specified. The macro-scale stiffness of the 3D woven composite pipe was obtained by averaging the stiffness on unit cells from micro-scale to meso-scale. The stiffness prediction is in good agreement with experimental results. On the other hand, using the multi-scale unit cells, the converse stress analysis process under multi-axial loads was carried out, i.e. to transfer stresses from macro-scale to meso-scale and finally to micro-scale. A model of embedding the meso-unit cell into a homogenous ring was suggested for meso-scale stress analysis in case of applied loads without periodicity in the annular direction. 