GB/T 21866-2025 "Test method for antiviral activity and antibacterial property of coatings" specifies a method for determining the antiviral activity and antibacterial property of coatings by comparing the number of surviving viruses and viable bacteria in test samples and control samples. It is applicable to coatings with relevant functions on architectural and wood surfaces, and coatings for other purposes may refer to this standard. The standard includes two core components: antiviral activity testing and antibacterial performance testing. It clarifies laboratory requirements, equipment and materials, reagents and culture media, test procedures, and result calculations, while adding appendix content covering the preparation of porous membranes, culture media formulation, determination of coating water absorption, and pretreatment.