GB/T 45512-2025 "Spinning & Weaving Products, Quantitative Chemical Analysis, Mixtures of Polybenzo Imidazole Fibers and Certain Miscellaneous Fibers" is a recommended national standard jointly issued by the State Administration for Market Regulation and the National Standardization Management Committee. The standard will be officially implemented on November 1, 2025, and stipulates the method of determining the fiber content in the two-component mixture of polybenzo Imidazole fibers and certain Miscellaneous fibers after removing non-fibrous substances by chemical analysis methods. The standard applies to the analysis of two-component mixtures of polybenzo Imidazole fibers and protein fibers, regenerated cellulose fibers, natural cellulose fibers and other fibers. As an important standard in the field of chemical analysis of Spinning & weaving products, its implementation will provide a unified detection method for the Spinning & weaving industry, promote product mass improvement and technological innovation.