Abstract: The effects of a new oxygenated diesel（independent oxygenated compound） and an oxygenated diesel blend（coal-based/oxygenated volume ratio is 1∶1） on combustion and emission characteristics were studied in a single-cylinder diesel engine in order to optimize its working characteristics in plateau environment. The results show that under constant boosting conditions,the power output and effective thermal efficiency of both oxygenated diesel and oxygenated diesel blend are improved,but the improvement degree of the two fuels show different with engine speed. The power and effective thermal efficiency of the oxygenated diesel fuel is slightly higher than that of the oxygenated blended diesel fuel at low speed and low load. With the increase of engine speed,the power output of the oxygenated diesel is higher than that of oxygenated diesel blend. However,under boosting conditions of plateau environment,the maximum power is increased by 6.50% and the corresponding effective thermal efficiency is increased by 14.00% for the oxygenated fuel at speed of 1 100 r/min,and the maximum power is increased by 1.68% at speed of 2 500 r/min. When the excess air coefficient is reduced to 1.6 at speed of 2 500 r/min,the power is increased by 11.20% and the corresponding effective thermal efficiency is increased by 1.97%. The NOx and particulate matter（PM） emissions from the oxygenated diesel are significantly reduced at all test conditions,with maximum decreases of 28% and 87%,respectively.