This paper introduces the working principle of Fibre Microscope and Metallographic Microscope, and their mutual calibration method. The calibration method is reasonable and easy to operate. Metallographic Microscope is widely used in metallurgy, manufacture, science and technology fields, and so on, for measuring the grain size of Austenite of metal material and the depth of Carburized layer after the heat treatment of the material. Fiber Microscope mostly measures the diameter, cross section and section acreage of all kinds of fibers. The key of the paper is to choose the best source of quantity values and the corresponding instrument. The quantity values of Fibre Microscope and Metallographic Microscope are traceable to the national standard. Moreover, the choice of suitable instrument can guarantee the quality control of the manufacturers.
