The ASTM E 2551-20 standard provides a standard test method for the Humidity calibration or validation of Humidity generators used by Thermal Gravimetric Analyzer (TGA). Humidity generators are commonly used in thermogravimetric analysis to simulate and control Humidity conditions during sample analysis. The standard specifies in detail how to calibrate Humidity generators to ensure the accuracy and Reliability of their output Humidity values. By adopting the method of this standard, the conformity of Humidity generators in operation can be effectively confirmed, and the experimental results of thermogravimetric analysis can be avoided due to imprecise Humidity control. This test method is of great significance for laboratories engaged in materials research, environment control and chemical analysis, and helps to improve Test accuracy and Reliability of data.