Abstarct: In this project copper nanoparticles and Cu-Al2O3 Nano-composites have been synthesized by mechanical milling method. Effect of many parameters such as milling time, speed, adding stearic acid as PCA, milling atmosphere and so on have been studied and the rule of Al2O3 weight ratio on the mechanical and electrical properties has been investigated for micro and nano sized composites. Experimental results show formation of copper dendrite structures by milling speed at 600 rpm during 10 hours. Increasing the milling time up to 30 hours formed flake structure which have been formed more quickly by adding stearic acid as PCA. By decreasing speed down to 450 rpm copper nano dendrite structures no further exist. Experimental results exhibit that Cu/3%wt Al2O3 Nano-composite show good mechanical and electrical properties for many industrial applications.