GB/T 611-2021 specifies a general method for the determination of density of chemical reagents. It describes the principle of density determination in detail, covering a variety of measurement methods such as density bottle method and Wechsler Balance method and their scope of application. Clear guidelines are given from the preparation of instruments and equipment, reagent Sample Handling, to the specific operation steps and result calculation. The standard unifies the chemical reagent density determination process, ensures accurate and reliable data, and provides an important density determination basis for the chemical industry, scientific research and other industries in terms of mass control of chemical reagents and performance research.