The standard describes a detailed method for measuring the relative strength of disperse dyes using the Spectrophotometric method, spec-trophotometry, which is applicable to all disperse dyes that comply with Lambert-Beer's law. The core principle is to dissolve the dyestuff sample with a solvent used in the master standard (such as dimethylmethylmethylmethamide acid solution), use a spectrophotometer to measure Absorbance at Maximum absorption wavelength, and calculate the relative strength of the sample according to Lambert-Beer's law. The key detection instrument specified in this method is a spectrophotometer, which requires its working Wavelength range to cover 380nm to 700nm and is equipped with a Cuvette with an optical path of 10mm. In addition, the standard also covers Miscellaneous essential equipment such as electric drying oven, High Accuracy Analytical Balance, volumetricflask and single-line straw. This method can provide a unified test basis for dyestuff production quality control, trade acceptance and Product Research & Development.