Abstract: To reveal the effect of opening position on pinned-joints mechanical properties and failure mechanism of 3D woven composites, three different 3D woven composite structures were designed and prepared, and the load-bearing performance and damage modes of these composites with different opening positions was discussed. The results show that there are differences in the effect of end-diameter ratio (E/D) on composites with different structural parameters. When the E/D decreases from 3 to 2, the ultimate compressive strength of three structural composites decreases by 5.3%, 9.9%, and 5.9%, respectively. When the E/D decreases from 2 to 1, the ultimate compressive strength decreases by 73.3%, 68.9%, and 69.8%, respectively. When the E/D changes from 3 to 1, the damage mode of the composites changes from extrusion damage to interfacial debonding, and the damage propagation of each yarn layer presents obvious angle features.