The present experimental work is conducted to examine the influence of adding Alumina (Al2O3) nanoparticles to diesel fuel on the characteristic of the emissions and engine performance. The size of nanoparticles which have been added to diesel fuel to obtain nano-fuel is 20 nm. Three doses of Aluminum oxide were prepared (25, 50 and 100) ppm. The nanoparticles mixed with fuel by mechanical homogenous (manual electrical mixer) and ultrasonic processor. The study reveals that the adding of Aluminum oxide (Al2O3) to gas oil (Al2O3+DF) enhances the physical properties of fuel. Also, the adding of (Al2O3) reduce CO emissions by 20.5%, decrease NOx emission by 12.2%, increasing CO2 emissions by about 2.27% and decrease UHC emission about 13.5%. Furthermore, reduces the brake specific fuel consumption by 14.3%, decreasing the equivalence ratio by14.87% and improving the brake thermal efficiency by about 10.89%.