An optical channel establishment method, for providing hierarchical management of the frequency spectrum in an optical network, characterized by comprising: establishing a media channel between a first node and a second node, wherein the media channel is established in a lower-layer media network, the first node is a source node of the media channel, the second node is a destination node of the media channel, and the media channel passes a frequency slot matrix of one or more intermediate nodes between the first node and the second node and an optical fiber between any two nodes among the first, intermediate and second nodes; allocating frequency spectrum to the media channel from available frequency spectrum of the optical fiber, wherein the media channel supports at least one single signal frequency slot; after the media channel is successfully established, forming, between the first node and the second node in an upper-layer signal network, which is corresponding to the lower-layer media network where the media channel exists, a traffic engineering link, which supports at least one signal channel, and the available frequency of which is the same as the frequency spectrum of the media channel, or in a case where the first and second nodes are directly connected with each other merely by an optical fiber, the available frequency of which is the same as available frequency spectrum of the optical fiber; establishing a signal channel between a third node and a fourth node, wherein the signal channel is established in the upper-layer signal network, the third node is a source node of the signal channel and the fourth node is a destination node of the signal channel, and the signal channel passes a frequency slot matrix of one or more intermediate nodes between the third node and the fourth node and the traffic engineering link; and allocating frequency spectrum to the signal channel from available frequency spectrum of the traffic engineering link; establishing a media channel between a first node and a second node, wherein the media channel is established in a lower-layer media network, the first node is a source node of the media channel, the second node is a destination node of the media channel, and the media channel passes a frequency slot matrix of one or more intermediate nodes between the first node and the second node and an optical fiber between any two nodes among the first, intermediate and second nodes; allocating frequency spectrum to the media channel from available frequency spectrum of the optical fiber, wherein the media channel supports at least one single signal frequency slot; after the media channel is successfully established, forming, between the first node and the second node in an upper-layer signal network, which is corresponding to the lower-layer media network where the media channel exists, a traffic engineering link, which supports at least one signal channel, and the available frequency of which is the same as the frequency spectrum of the media channel, or in a case where the first and second nodes are directly connected with each other merely by an optical fiber, the available frequency of which is the same as available frequency spectrum of the optical fiber; establishing a signal channel between a third node and a fourth node, wherein the signal channel is established in the upper-layer signal network, the third node is a source node of the signal channel and the fourth node is a destination node of the signal channel, and the signal channel passes a frequency slot matrix of one or more intermediate nodes between the third node and the fourth node and the traffic engineering link; and allocating frequency spectrum to the signal channel from available frequency spectrum of the traffic engineering link;