Abstract: Based on the meso-structure of 3D full five-directional (Q5D) braided composites, a nonlinear finite element model with interface phase was presented to simulate the damage and failure of Q5D braided composites under unidirectional tension by introducing the interfacial phase element. The failure criteria proposed by Linde and Von-Mises criteria were considered for initial damage prediction of yarns and matrix. Quads failure criteria was adopted to identify the onset of debonding of the interface phase. The progressive damage of Q5D braided composites with interface phase was studied subjected to longitudinal tensile loading, and ultimate strength of the sample was obtained. The damage mechanisms were revealed in the simulation process and the changing characteristics of mechanical behaviors of braided composites with the interfacial properties were described. The results show that the numerical simulation results are in a good agreement with experimental results, which validate the effectiveness of the model and provide a basis for the analysis of mechanical properties and optimization design of structures.