As an imaging tool of nanometer resolution for microstructure analysis, the scanning electron microscope plays an important role in semiconductor and nanometer structure measurement. In this study, a special scanning electron microscopy imaging and line width measuring method is introduced based on principle of laser interference. We design the double stages including micron resolution stage and nanometer resolution stage. A new imaging mode by raster scanning of precision stage is employed in this metrological scanning electron microscope. The line width of standard sample image is measured precisely by calculating the coordination data that come from the laser interferometer system. This nanostructure measuring method is in line with international standard for the dimension measurement of traceability.