Optical methodological analysis is a kind of method to analyze the measured sample according to the emission or absorption of electromagnetic radiation and the interaction between material and electromagnetic radiation. There are three types: (1) emission spectrochemical analysis, flame photometric analysis, fluorescence X-ray spectrometry, fluorescence analysis and atomic fluorescence spectrometry based on emission principle; (2) colorimetric analysis, turbidity analysis, infrared absorption spectrometry, atomic absorption spectrometry analysis based on absorption principle; (3) other principles X-ray diffraction analysis, electron microscopy analysis and polarization analysis are also included.