A mobile phone anti-theft system includes a mobile phone, a SIM card and a real-name card-issuing system. The real-name card-issuing system includes a central processing unit, a first user information storage area, transmission equipment, and a card reader. The SIM card communicates with the central processing unit through the card reader and the transmission equipment. The real-name card-issuing system sends user information stored in the first user information storage area to the SIM card. If the SIM card needs to change the user information, it should verify first cryptographic keys with the real-name card-issuing system. The mobile phone includes a micro control unit, a second user information storage area and a transmission unit. The SIM card communicates with the micro control unit through the transmission unit. After each startup of the mobile phone, the mobile phone verifies second cryptographic keys with the SIM card.