Abstract: How to reduce cost and prevent waste in using heat conducting oil is a question valuable to be discussed. Using blended heat conducting oil of different quality is really a good method for cost reducing. Analyzes a using possibility of blended heat conducting oil and carries out blending test of heat conducting oil in synthetic and mineral oil types. Points out that heat conducting oils of different quality can be blended used if they have approximate chemical composition and no responsive action between additives, and meanwhile, puts forward an estimate method on physical property of the blended oil.