In this study, when Butyl ether, a type of diether-based oxygenated fuel, is mixed in each volume ratio in a naturally aspirated direct injection diesel engine, the exhaust gas emission characteristics of the oxygenated component in the fuel affect each operating area of the engine I wanted to investigate the effect on. For comparative measurement of engine performance and exhaust emissions, commercial diesel and butyl ether mixed fuels were classified into 4 types according to the mixing ratio and tested. As the content of butyl ether in fuel increases, soot emission reduction increases, and when the maximum mixing amount of butyl ether (diesel 80vol-% + BE 20vol%) is applied, compared to the case of using only diesel as fuel, at 2500 rpm and no load, 39%, and about 32% of smoke reduction effect at full load was confirmed.