Mechanical properties such as tensile, shear and interlaminar shear of multi-nanostitched three dimensional (3D) carbon/epoxy composites were studied. Introducing the polyacrylonitrile (PAN) nanostitched yarn into carbon preform composite marginally decreased the tensile properties, whereas it improved the shear and interlaminar shear properties. Multi-nanostitched 3D carbon/epoxy composite under the tensile loading suppressed the layer-to-layer opening and failure mode included multiple brittle fiber and matrix tensile breakages at local region. On the other hand, delamination propagation under shear loading was inhibited via angular deformation of the multi-nanostitching fibers. Additionally, all of the structures under the short beam loading experienced angularly sheared fatal layer breakage in the z-direction and interlaminar delamination was arrested in the multi-nanostitched composite due to the nanostitching insertion in the composite during preform formation.