A method, device and system for automatically discovering optical fiber connection within a network element are provided. In the method, a destination board determines whether it is connected with a source single board for the first time according to a triple group message received within a predefined period and sent by the source single board, and if yes, sends a sextuple group message generated based on its triple group message to an ASON, and stores the sextuple group message in a local database; otherwise, it sends the sextuple group message stored in the local database and corresponding to the triple group message, to the ASON when timing is reached; when receiving the sextuple group message and determining that the sextuple group message is not stored locally, the ASON detects validity of a connection corresponding to the sextuple group message, and locally stores the sextuple group message if the connection is valid, otherwise, displays connection error information to a user.