A method for establishing a multi-carrier optical cross-connection, comprising: determining (S101a), by a first node, the number of subcarriers, spectrum bandwidth of a single subcarrier, and non-overlap of spectrum resources between neighboring subcarriers of a connection; obtaining (S102a), by the first node, a first set of available center frequencies of a first link according to the spectrum bandwidth of a single subcarrier, wherein the first link is a link between the first node and a neighboring node in a direction from the first node to a second node; sending (S103a), by the first node, a request message to the neighboring node in the direction from the first node to the second node, wherein the request message carries at least the number of subcarriers, information on the spectrum bandwidth of a single subcarrier, subcarrier overlap attribute information, and information on the first set of available center frequencies, and the subcarrier overlap attribute information indicates the non-overlap of spectrum resources between neighboring subcarriers; and receiving (S104a), by the first node, a response message, extracting information on a set of center frequencies of subcarriers out of the response message, and obtaining the set of center frequencies of subcarriers of the connection; and establishing (S105a) an optical cross-connection based on a spectrum range determined according to the non-overlap of spectrum resources between neighboring subcarriers, the set of center frequencies of the subcarriers, and the spectrum bandwidth of a single subcarrier, wherein, the set of center frequencies of the subcarriers is composed of available center frequencies with a non-overlap frequency range which are selected by the second node from a second set of available center frequencies; and the second set of available center frequencies is an intersection of sets of available center frequencies of all links traversed by the connection, wherein the sets of available center frequencies are obtained according to the spectrum bandwidth of a single subcarrier. determining (S101a), by a first node, the number of subcarriers, spectrum bandwidth of a single subcarrier, and non-overlap of spectrum resources between neighboring subcarriers of a connection; obtaining (S102a), by the first node, a first set of available center frequencies of a first link according to the spectrum bandwidth of a single subcarrier, wherein the first link is a link between the first node and a neighboring node in a direction from the first node to a second node; sending (S103a), by the first node, a request message to the neighboring node in the direction from the first node to the second node, wherein the request message carries at least the number of subcarriers, information on the spectrum bandwidth of a single subcarrier, subcarrier overlap attribute information, and information on the first set of available center frequencies, and the subcarrier overlap attribute information indicates the non-overlap of spectrum resources between neighboring subcarriers; and receiving (S104a), by the first node, a response message, extracting information on a set of center frequencies of subcarriers out of the response message, and obtaining the set of center frequencies of subcarriers of the connection; and establishing (S105a) an optical cross-connection based on a spectrum range determined according to the non-overlap of spectrum resources between neighboring subcarriers, the set of center frequencies of the subcarriers, and the spectrum bandwidth of a single subcarrier, wherein, the set of center frequencies of the subcarriers is composed of available center frequencies with a non-overlap frequency range which are selected by the second node from a second set of available center frequencies; and the second set of available center frequencies is an intersection of sets of available center frequencies of all links traversed by the connection, wherein the sets of available center frequencies are obtained according to the spectrum bandwidth of a single subcarrier.