A channel establishment method and device are provided. The method includes: establishing a media channel between a first node and a second node; establishing a signal channel between a third node and a fourth node after the media channel is established, wherein the signal channel passes a frequency slot matrix of one or more intermediate nodes between the third node and the fourth node and a traffic engineering link between any two nodes; and allocating frequency spectrum to the signal channel from available frequency spectrum of the traffic engineering link, wherein the frequency spectrum includes multiple split frequency spectrums which bear one optical channel and each of which contains a plurality of optical carriers or only contains a single optical carrier. The solution can address the problem as to how to effectively plan and manage frequency spectrum for an introduced flexible grid technology and improve waveband frequency spectrum efficiency.