This standard test method is used for the measurement of the cross-sectional thickness of metallic coatings by Scanning Electron Microscope (SEM). It is suitable for direct measurement of the thickness of various layers of metals and composite coatings, especially for thin layers that are difficult to measure by OpticalMicroscopy. This method is not only suitable for acceptance tests, but also can be used for accurate thickness measurement of coatings, especially at high magnification. Through this method, it is possible to understand in detail the effect of the thickness of the coating on its performance, but it is necessary to note that the fineness of sample preparation is crucial to the accuracy of the measurement results.