A Transparent Interconnection of Lots of Links (TRILL) network establishing method, node, and system. The TRILL network establishing method includes: receiving, by a first node, a Link Layer Discovery Protocol (LLDP) packet, where an optional type-length-value (TLV) field of the LLDP packet includes TRILL capability information of a second node that sends the LLDP packet; and if it is determined, according to the TRILL capability information, that the second node has a TRILL capability, and the first node itself also has the TRILL capability, configuring, by the first node, a port, through which the LLDP packet is received, of the first node, to have a TRILL function enabled. The node in embodiments of the present invention can automatically enable or disable the TRILL function, so as to implement automatic establishment of a TRILL network.