The fish scale polypeptide has an inhibitory activity on angiotensin converting enzyme. Therefore, it is a very important means to recover the fish scale by decalcifying the fish scale and preparing a certain active polypeptide by enzymatic hydrolysis. However, a large amount of inorganic salts remain in the enzymatic hydrolysis process, which affects the activity. Therefore, more and more researchers are beginning to use adsorption resin treatment as the first step in the separation and purification of enzyme products. Suzhou Bojie Resin Technology Co., Ltd. provides macroporous adsorption resin not only to achieve desalination at the same time, but also to obtain components of different polarities. The method is simple and easy to operate, low in cost, large in processing amount and short in time, and exhibits obvious advantages in separation and purification of the polypeptide.