In this study, the effect of oxygen-enriched air (10% enrichment) on the performance characteristics (brake power, brake torque, brake mean effective pressure, brake specific fuel consumption, brake thermal efficiency) of a gasoline internal combustion engine (EF7) has been investigated by using GT-Power software. The simulation was lunched at different engine speeds (1000, 2000, 3000, 4000, 5000 and 6000 rpm). The GT-Post post processing plots the performance parameters versus engine speed. The results of study showed the brake power, brake torque and brake mean effective pressure increase 9.5 to 11% for oxygen-enriched air condition. Also according to the results there is no deference between oxygen-enriched air and normal conditions in BSFC and BTE values. Although the results showed that BSFC and BTE increase slightly in oxygen-enriched air condition than that of normal condition at higher engine speeds.