In this work, 500 PPM concentration of Al2O3 nanoparticles (40 nm size) are utilized as fuel additives in a 4-stroke, single-cylinder, water-cooled CI engine along with the biodiesel forms B10, B20, and B30 produced from rice bran. The engine operates at constant speed of 1500 RPM, 0 kW to 3.5 kW load, and 17.5:1 mm compression ratio. For this experimental effort, nano fuel is prepared by the ultrasonication technique.Using a magnetic stirrer, eight different samples of nano-added mixed fuels, including B10Al2O3500, B20 Al2O3500 and B30Al2O3500, have been synthesized. All RBME biofuel nano additive fuel blends were analyzed on CI engine characteristics, and the results were then compared to the characteristics of neat diesel fuel. The primary goal of this research is to strengthen the engine's performance and combustion attributes while degrading NOX, CO2, CO, and HC exhaust emissions into the environment.In this research, BSFC, BTE, and EGT engine performance indicators enhanced in contrast to neat diesel although NOx, CO, CO2, and HC exhaust emission dropped by 25.45%, 58%, 3.52%, and 18.12%, respectively. However, this experimental study's use of all types of blended fuels resulted in a modest improvement in loudness. Diesel engine performance and combustion characteristics significantly increase during using Al2O3 nano addition in biodiesel blend fuel.