This standard specifies three mass grades of laboratory water, including technical requirements for primary, secondary and tertiary water. The standard details the limits of pH value, conductivity, specific resistance, oxidizable substances, Absorbance, evaporation residue and soluble silicon for different grades of water. Primary water has the most stringent purity requirements, such as pH value, specific resistance and conductivity, all of which must meet the highest standards; secondary and tertiary water are suitable for general laboratory use, and their index requirements are relatively loose. This standard ensures that the mass of laboratory water adapts to different experimental needs, improving the accuracy and Reliability of experimental results.