The anisotropic mechanical reinforcement compression and scratch resistance of epoxy nanocomposites filled with well‐aligned carbon nanotubes (ACNTs) sliding in different orientations were investigated by nanoindentation techniques. It was found the addition of ACNTs to epoxy very effectively improved the microscopic hardness, elastic modulus, and nanoscratch resistance of pure epoxy, and the nanocomposites in antiparallel orientation of ACNTs showed the highest enhancement. However, macroscopic compression test showed the normal orientation of ACNTs enhanced the compression strength the most. Based on nanoscale observations, new ACNTs related reinforcing and scratch resistance mechanisms were further proposed and discussed. This study will enhance the understanding of the anisotropic reinforcement effect of ACNTs with new characteristics, and will be helpful for the design and application of ACNT nanocomposite materials into precision instruments and related anisotropic nanomaterials.