It is well known that gears are one of the most important and common machine components, andrnun alternative, light weight and durable, material for gears has been the focus of many researchers,rnespecially in the last two decades. This thesis work will focus on assessing the capability ofrnpolymer composite spur gear, acetal, which is the most commonly used polymer for gearrnmanufacturing due to its manufacturability, low cost, and good wear resistance, reinforced withrnnano-silica (spherical), one of the most easily available and widely used nano particle to reinforcernthermoplastics, for medium power transmission(890W). Reinforcing polymers with nano-particlesrnis found to be one of the most effective methods to improve the overall mechanical and thermalrnproperty of polymers. The composite gear performance is analyzed for wear and thermal resistancernas well as fatigue life. The analysis is conducted with the aid of FEM software Abaqus/CAE 6.14rnand the homogenized material property of the composite is predicted using the multi scalernhomogenization technique which was found to be reliable for calculating the homogenizedrnmechanical property of polymer nano-composites. The results obtained after this work show thatrnthe addition of 4.5 volume percentage of nano-silica (SiO2) in to the polymer matrix (acetal) wasrnfound to increase the wear resistance by 300%, the thermal conductivity by 47% and the numberrnof cycles to fatigue failure was found to be ten times more than pure acetal gear, where the changernor increase in mass of the gear is only 15.86 grams.rnKey words: nano-composite, spur gear, wear resistance, thermal resistance, fatigue life, FEMrnanalysis