A protection system for a display apparatus and a method thereof are provided. The protection system includes an electronic key and a protection module. The protection system performs security identification with a plurality of passwords and updates the passwords every time after the security identification is completed to improve the security of the display apparatus. The display apparatus is allowed to be turned on when one of the passwords is correct, and the passwords are separately updated after the security identification is completed. The protection system is highly secure and provides greater convenience to users.