Nano-composites manufacturing is one of advance manufacturing technique in the history of materials. Friction stir processing (FSP) is an emerging surface engineering technology that can produces nano-composites and homogenous microstructures locally, thereby improving the mechanical properties. This paper presents the effect number of passes on Mechanical Properties of SiO2/5083 Al Metal matrix nano-composites fabricated by friction stir processing and microstructure.Fabrication of in situ SiO2/5083 Al Metal matrix nano-composites using multi-pass (One Pass, 2 Passes, 3 Passes, and 4 Passes) at rotation speed 400 rpm, and tool travel speed 100 mm/min. In general it is found that, FSP optimum condition it single pass, at this condition increases the ultimate tensile strength (UTS) up to about 110.6 % elongation percentage up to about 132.1 % micro-hardness number up to about 131.7% and impact energy up to about 125.4 from the base material. Also, coarse second phase particle fragmentation and grain refining are observed. Both macrostructure and microstructure observations indicate homogenous microstructures locally of SiO2/5083 Al metal matrix nano-composite Fabricated by friction stir processing.