This standard specifies the method for determining the fixation rate of reactive dyestuff in the process of pad dyeing. It is suitable for measuring the fixation rate of reactive dyestuff after pad dyeing to evaluate the setting effect of dyestuff on fibers. The calculation method of fixation rate includes two kinds: one is based on the total amount of dyestuff, calculating the ratio of setting dyestuff on the fiber to the total amount of dyestuff put into the dye bath; the other is based on the proportion of dyestuff amount on the fabric before and after fixing. Through the treatment of dyed fabrics, such as roll dyeing and subsequent heat treatment, etc., to ensure the uniform distribution and setting of dyestuff, and finally determine its fixation effect. This method helps ensure dyestuff durability and Stability in Spinning & Weaving products.