Fresh jellyfish contains toxins, which can't be eaten directly. It must be treated correctly before eating, otherwise it will lead to poisoning. Fresh jellyfish just caught are immediately put into a porcelain jar or canvas bag, and alum is prepared according to the proportion of 0.2% ~ 0.6% of the weight of fresh jellyfish, dissolved in water and pickled for 2 days to make the fresh jellyfish converge and discharge water, which is called "primary alum". Then add salt12% ~ 20% and alum 0.5% ~ 0.8% according to the weight of the initial alum jellyfish, and then pickle for 7 days ~10 days to further remove water, which is called "two alum and one salt". Finally, add 20% ~ 30% salt and 0.2% ~ 6.3% alum according to the weight of Erfan jellyfish, and then pickle for 10 day. In this way, after about three weeks, the water content of the sting skin will be reduced to about 8% ~10%, so that the toxin can be discharged with the water. Finally, the detoxified jellyfish should be soaked and rinsed repeatedly with clear water until the salt and alum are completely removed. At this time, the jellyfish is light red or light yellow, with uniform thickness and toughness. If it is squeezed hard, it can't squeeze out water, so it can be safely eaten.