A method and apparatus for transmitting data in an Android platform based terminal device are provided. In the method, when the terminal device establishes a connection for data transmission with another device over a USB, the terminal device transmits data in an internal storage of the terminal device to the another device based upon a file transfer protocol and receives and writes into the internal storage data transmitted from the another device based upon the file transfer protocol; and the terminal device transmits data in an external storage of the terminal device to the another device in a UMS mode and receives and writes into the external storage data transmitted from the another device in the UMS mode.