A channel establishment method and device are provided. The method includes: establishing a media channel between a first node and a second node, wherein the first node is the source node of the media channel, the second node is the destination node of the media channel, and the media channel passes the frequency slot matrix of the one or more intermediate nodes between the first node and the second node and the optical fiber between any two nodes; and allocating frequency spectrum to the media channel from the available frequency spectrum of the optical fiber, wherein the media channel supports at least one single signal frequency slot. The solution can address the problem of how to effectively plan and manage frequency spectrum for an introduced flexible grid technology.