In the current research, the effect of nano Zirconium dioxide (ZrO2) on the buckling strength of epoxy resin based composite was studied experimentally before and after applying damage. The nano particles were added to the epoxy resin matrix with 1-4 wt% of the composite. The applying damage to the samples was made with two kinds of cutting drilling tools: flat end and ball end drilling tools and with 1.5 and 3 mm depth of hole. The buckling tests were done for neat epoxy composites without nano particles and for nano composite samples before and after drilling and compared with each other. The results obtained from tests showed a good enhancement on the buckling strength of nano composites about 50% for samples with 3 wt% of nano Zirconium dioxide. Also, the drilling process, was decreased the strength of composites, but the adding nano Zirconium dioxide retrieved this failure and increased the buckling strength of nano composite after drilling in comparison with the neat samples. Finally, the SEM showed a good dispersion of nano particles in the epoxy matrix and made a smooth surface. (C) 2018 Elsevier B.V. All rights reserved.