The principle of enzyme-linked immunosorbent assay (ELISA) is to bind antigens or antibodies to the surface of a solid carrier and maintain their immune activity. Linking an antigen or antibody to an enzyme to form an enzyme-linked antigen or antibody that retains both its immune activity and enzyme activity. Wash the antigen antibody complex formed on the solid-phase carrier to separate it from other substances, and then the amount of enzyme bound to the solid-phase carrier is proportional to the amount of the test substance in the specimen. After adding the substrate to the enzyme reaction, the substrate is catalyzed by the enzyme to become a colored product, and the amount of the product is directly related to the amount of the analyte in the specimen. Therefore, qualitative or quantitative analysis can be performed based on the intensity of the color reaction. Due to the high catalytic frequency of enzymes, the reaction effect can be greatly amplified, thereby achieving high sensitivity in the measurement method.