GB/T 35166-2017 requires the Humidity reaction method to determine the absorption/moisture release performance of building materials and products. The standard details the Humidity reaction test device, which can precisely control various parameters of the Humidity environment. The material specimen is placed in the device, and the mass change of the specimen under different Humidity conditions is monitored by changing the Environmental humidity, so as to calculate the material absorption/moisture release amount, and then evaluate its absorption/moisture release performance. This provides key data support for the application of building materials in different Humidity environments, which helps to rationally select materials, optimize the adjustment of Humidity inside the building, and improve indoor comfort and building durability.