The scientific importance of nanocomposites is being increased due to their improved properties. In the current paper, the relationship between the reinforcement weight fraction and Tensile properties of Al/Al2O3 (with a reinforcement weight fraction of 0, 2.5, 5 and 10 wt%) synthesized by high energy ball milling is studied. Scanning electron microscopy analysis, X-ray diffraction analysis and transmission electron microscopy are used to characterize the produced powder. The results show that the addition of Alumina particles accelerates the milling process, leading to faster work hardening rate and fracture of the aluminum matrix. Moreover, Al crystallite size become refined during ball milling of Al powder in the presence of Al2O3 particles. Uniform distribution of nano-sized Al2O3 particles in the Al matrix could be achieved with increase in the reinforcement weight fraction. The microhardness of the composite increases with the increase of the reinforcement weight fraction and it reaches 94 HV at 10 wt% Al2O3 composite. The yield strength and ultimate strength of the composite are also increased by increasing the reinforcement weight fraction.