The present invention discloses a USB memory card such as an intelligent stick, of which a control of data encryption is included to enhance data security and meet the data security requirement. The USB memory card of this invention is applicable for the traditional smart card market, like as e-commerce, ID token in internet, as well as featuring a low system cost and a popular USB interface. The size of such USB memory card is small, easy-to-carry, and easy-to-use.