After the fiber is harvested with flax, it is bundled into small bundles for retting and degumming. The temperature of retting flax with warm water should be controlled between 28~32 ℃. After about 100 hours, it should be fished out. The hemp pole should be put up into an umbrella shape and dried in the open. Dew flax retting is to lay the harvested flax stems on the grass or flax ground, and make them by fermentation with mold after being soaked in rain and dew. Under the appropriate humidity conditions, after 7-10 days, the retted dry stems shall be broken, the xylem and impurities shall be removed, the fibers shall be combed, and then the number shall be divided according to the quality. The short hemp that has been knocked off is called the second coarse hemp.