Standard HG/T 4657-2014 "Spinning & weaving dyeing and finishing aids, catalase, enzyme activity" specifies the determination method of catalase activity in Spinning & weaving dyeing and finishing aids. This standard is suitable for evaluating the enzyme activity of catalase dyeing and finishing aids used in the deoxygenation process of fabrics. During the determination process, ammonium molybdate is used as a catalyst, hydrogen peroxide reacts with potassium iodide to generate free iodine, and then the amount of unanalyzed iodine is determined by sodium sulfate titration to calculate the amount of hydrogen peroxide that has not been analyzed, and then the amount of hydrogen peroxide that has been analyzed is calculated. This method ensures the accurate determination of catalase activity to ensure the effect and mass during dyeing and finishing.