The invention discloses microemulsion diesel oil with good thermodynamic stability and belongs to the field of energy chemistry. The formula is characterized by consisting of diesel oil, water and a total assistant, wherein the total assistant is composed of di-mycolic acid fungal acid trehalose, sophorolipid, trehalose glycolipid, lipopolysaccharide complex, lipopeptide, sulfonated betaine, lignin sulfonate, oleic acid, cholamine and amyl nitrate. The microemulsion diesel oil disclosed by the invention is good in thermodynamic stability, good in combustion effect, small in viscosity and free of oil-water stratification phenomenon after long-term storage. Moreover, the microemulsion diesel oil disclosed by the invention can be used for stably improving the vaporization rate of diesel fuel, and the secondary atomization effect of the microemulsion diesel oil ensures more full contact between the diesel fuel and the oxygen, so that the combustion of the diesel fuel is more full; compared with common diesel oil, the oil saving rate of the microemulsion diesel oil disclosed by the invention is larger than 10%, and the tail gas emission is excellent superior than that of national standard diesel oil.