GB/T 19587-2017 "Determination of specific surface area of solid substances by gas adsorption BET method" is a national standard for the determination of specific surface area of porous solid materials based on the principle of gas adsorption. Its core is to use the BET multi-layer adsorption theory to calculate the saturation adsorption of the monolayer of the material by measuring the adsorption amount of the material to nitrogen and other gases at the temperature of liquidnitrogen, so as to obtain the specific surface area value. The standard is equivalent to international standards and is suitable for non-porous or mesoporous materials such as powders and particles. According to the standard, the test requires the use of a gas adsorption analyzer, which mainly includes two categories: one is an instrument using the static capacity method, which needs to accurately measure the gas pressure and volume in a vacuum environment; the other is a fully automatic ratio Surface Analyzer using the dynamic flow method, which can achieve rapid and continuous determination under normal pressure.