A method for offline DRM authentication and a system thereof relates to the information security field. In order to solve the problem that a license must be requested from the server in the process of DRM authentication, the invention provides a method for offline DRM authentication, in which, the method comprises: a content provider encrypts the data file with DRM standard and stores the internal information in an authentication device, the authentication device is connected to the local computer, the software program on the local computer opens and reads the data file. A system for offline DRM authentication, in which, the system comprises an authentication device, a client PC and content provider side, the authentication device comprises the DRM service module and authentication communication module. Compared with the prior art, the present invention allows the user to use the DRM protected information without a network connection.