The invention provides a mobile terminal anti-theft method and device. An operation instruction (the operation instruction comprises a powerboot instruction or a standby waking instruction) input by a user is received; when detecting that the identity information of a legal user bound with the mobile terminal and the card information of a legal SIM card bound with the identity information are pre-stored in the mobile terminal and an SIM card is arranged in the mobile terminal, the card information of the SIM card is read; the identity information of a user is obtained; when the obtained identity information of the user does not conform to that pre-stored in the mobile terminal, or the read card information does not conform to that pre-stored in the mobile terminal, the action corresponding to the operation instruction is forbidden; in this way, when the current using user of the mobile terminal is illegal, or when the current SIM card in the mobile terminal is illegal, the condition that the mobile terminal executes the action corresponding to the operation instruction is effectively avoided; and the security of the data in the mobile terminal is effectively ensured.