The present application discloses a link discovery method and apparatus. The method includes: when a network device receives a first LLDP packet sent by a directly connected device, determining a security level of the directly connected device according to an authentication TLV; if the security level of the directly connected device is secure, determining a device type of the directly connected device, and sending a second LLDP packet to the directly connected device according to a correspondence between the device type of the directly connected device and a TLV. In the present application, a corresponding TLV is selected according to the device type and sent, which avoids that all types of TLVs are sent to a directly connected device every time, and reduces a possibility of device information leakage. It is ensured that a sent LLDP packet is more proper, and a link overhead is reduced.