The invention provides a preparation method of novel lubricating oil. The method comprises the following steps: a. mixing base oil, mixed amide and modified graphite, and stirring at a high speed to obtain a mixture I; b. adding an antioxidant and a polymeric dispersant into the mixture I, stirring and blending, and adjusting the pH value to obtain a mixture II; c. adding additives and ionic liquid into the mixture II, stirring and blending to obtain a mixture III; d. ultrasonically dispersing the mixture III, and then filtering to remove impurities so as to obtain the finished product. The lubricating oil prepared by the method shows excellent extreme pressure resistance and high carrying capacity, is good in wear resistance, and also can provide excellent long-acting lubricating property.