This standard specifies the method of picking Colorimetric test of coking naphthalene, including the preparation of reagents and solutions, the use of instruments and equipment, the collection and preparation of samples, test procedures, result judgment and test report. This standard is applicable to the picking Colorimetric test of coking naphthalene extracted from coal tar. The Colorimetric number of the sample can be effectively determined through standardized operation, to ensure the conformity and comparability of the product mass, and to provide a reliable detection basis for related industrial applications.