This standard specifies the test method for detecting the particle size of ion-exchanged Resin and limestone powder by laser diffraction, which is applicable to the particle size range of 0.1 μm~ 2.0 mm. The term includes the characteristic particle size of limestone powder. The method outline is to disperse the sample in the saline water and use the principle of laser diffraction to detect the particle size. The required instruments and equipment include laser diffraction analyzer, glass tube and labspoon, and the reagent water should meet the specified requirements. The sample preparation should meet the relevant standards.