In view of the problems that cutting fluid is still used in the process of machine tools and their cleanliness degree is too low, a cleanliness improvement method of machine tool remanufacturing based on minimal quantity lubrication is proposed. This method introduces the technology of minimal quantity lubrication to implement cleanliness improvement for used machine tools based on remanufacturing, including the procedures of analysis of cleanliness problem and pollution source of used machine tools, feasibility analysis of cleanliness improvement by remanufacturing, selection and design of equipment of minimal quantity lubrication (including mechanical piping system design and electrical control system design), structure matching and redesign of used machine tools, and so on.The application case of a gear cutting machine shows that the use of minimal quantity lubrication can improve the cleanliness of used machine tools effectively, and the economic and environmental benefits are remarkable.