Abstract: On the basis of available studies, a new model of representative volume elements of 3-D braided composites is proposed, which truly reflects the braided manner and coincides with the actual configuration of the braided composites. It can be used to predict the effective modulus of 3-D braided composites with Finite Element Method (FEM) and determine its stress field in reason. The finite element software was adopted to study the mechanical properties of this model, and the effective properties of elasticity were obtained. The results show that the ones of finite element calculation fit well with the experimental results and theoretical prediction, which demonstrates the validity of this model. In addition, based on the new model, the stress field of 3-D braided composites in tension or shearing is determined, which provides the basis for strength calculation in the future.