Abstract: A numerical method, cell-element method, which establishes the relation between microstructure and macro-response in 3D braided composites is presented in this paper. Firstly, a 3-D braided composite structure is meshed by the unit cells, then based on the analysis of the micro-structure, the variables of the micro-structure are translated into the variables of macro-nodes, and the stiffness of the cell-element is formulated. The numerical results show that this method can feedback the response of macro-variables to any tiny change in the micro-structure.