This invention provides a portable index device with briefcase and its realization method. The method includes the steps of: connecting the index device to a computer; changing configuration information and a route of personal favorite files in the computer, and recording the changing information of the personal favorite files in a default file in the computer; pointing the computer configuration information and the route of the personal favorite files in the computer to the computer configuration information and the personal favorite files in a memory cell; the computer receiving user operation instruction or an index position identifying instruction input by an input unit, operating the computer according to the user operation instruction or the index position identifying instruction; when the electrical connection of the index device and the computer is over, recovering the route of the personal favorite files and the configuration information in the computer according to the recorded information in the default files. The invention enables to use some important information at any moment, and when uses the computer of other's, ensures the data of other person safety and security.