This paper was motivated by designing three-dimensional five-directional structure with the non-periodic characteristics by the process of the yarn reduction.Then carbon/epoxy three-dimensional five-directional braided composites were prepared.The universal material testing machine and the high speed camera were employed to the tensile mechanical behaviors and damage process.Furthermore,the progressive damage and final failure images were observed by using Micro-CT and scanning electron microscope (SEM).The failure mechanism of non-periodic braided composites were analyzed and compared with that of the periodic samples.The results show that the tensile strength of non-periodic 3D braided composites is 16.84% lower than that of periodic materials with the same structural parameters.The damage of non-periodic three-dimensional braided composite material is derived from the yarn reduction,and the stress concentration is formed,and the ultimate failure mode is based on the fiber bundle pulling fracture.The results of this study can provide a basis for structural design and strength analysis of special-shaped braided composites.