Data protection method and device used for terminal external storage card

The invention provides a data protection method and device used for a terminal external storage card. The data protection method and device used for the terminal external storage card comprises the following steps: at least one secret key and a corresponding encryption/ decipherment algorithm are stored in a terminal; an incidence relation is established between at least one application and at least one secret key stored in the terminal; and when the application is detected to need to read/write data in the external storage card, the secret key relevant to the application is obtained and the encryption/ decipherment algorithm corresponding to the secret key are used to read/write the data. On the condition that normal reading and writing of the data are not affected and when the data storage card is obtained by other people, the data protection method and device used for the terminal external storage card can ensure that data information can be effectively prevented from being viewed, copied and spread at will.