Abstract: Diglyme, diethyl adipate and biodiesel were selected as oxygenated additives to mix with diesel in different proportions, respectively，to investigate the combustion characteristics of fuels under the oxygen deficient conditions by low pressure oxygen bomb calorimeter. The efficiencies were evaluated by the combustion improvement factor Ψ. The results show that the three oxygenated additives can all improve the combustion of diesel fuel under the oxygen deficient condition. The combustion efficiency is concerned with the calorific value and the oxygen content of the oxygenated additive. At the altitude of 3000 meters, the best oxygenated additive is Diglyme, and the perfect dosage is 18%.