Provided are a mixed nano-lubricating oil and a method for preparing the same. The method for preparing a mixed nano-lubricating oil includes the steps of: (a) preparing a mixed solution by adding and mixing a nanopowder and a dispersant to a solvent and pulverizing the nanopowder to a primary particle level; (b) modifying the surface of the nanopowder; (c) substituting the solvent of the mixed solution to a lubricating oil; and (d) mixing at least two nano-lubricating oils prepared using physically and chemically different nanopowders. According to the present invention, it is possible to improve the wear resistance and the load resistance at the same time by mixing at least two kinds of lubricating oils having excellent wear resistance or load resistance.