The invention relates to a method for realizing link discovery and management in an FTTX (Fiber to the X) access system. The method comprises the steps of: periodically sending link layer discovery protocol messages to an uplink device of an OLT (Optical Line Terminal) device through an uplink interface by the OLT device; performing a listening task by a core swap disk program of the OLT, wherein the link layer discovery protocol messages from an ONU (Optical Network Unit) and an ONU user-side access device are received in the listening task; respectively storing locally stored information of the device and information of a user-side network device into a local link layer discovery protocol management information base by the OLT device; requiring to send LLDPDU (Link Layer Discovery Protocol Data Unit) protocol messages to the uplink device by the OLT so as to report the existence of the OLT; and carrying out extension of the LLDPDU messages. The invention fills in the gap of application of the traditional link layer discovery protocol (LLDP) and provides the method for realizing link layer discovery in the FTTX access system with optical path grading, especially on a plug-in card type OLT device; and according to the method, provided by the invention, the basic architecture of the FTTX access system is not affected, and the operation is simple and easy to realize.