The working principle of the supermarket anti-theft system is: attach an electronic anti-theft tag to the goods that are small in size, large in value and easy to be stolen, and there is an anti-theft door at the exit of the mall. When the thief steals the goods with the tag through the inspection door, he will immediately call the police (like the boarding check at the entrance of the airport), while the normal shopping will make the tag invalid and will not call the police when passing the cashier. For supermarkets and clothing stores that often lose goods, Franchise stores and other business places can greatly reduce losses