Provided are a method, an apparatus and a system for establishing an optical bypass. The method includes: a route controller sending an optical bypass establishment request carrying information about an ingress node, an egress node and a required bandwidth to an optical transmission controller; and setting a second flow forwarding entry corresponding to the optical bypass for the ingress node and the egress node and sending the set second flow forwarding entry to the ingress node and the egress node when receiving an establishment success notification sent by the optical transmission controller, the establishment success notification being used for indicating that the optical transmission controller has allocated the optical bypass according to the optical bypass establishment request, set a first flow forwarding entry corresponding the bypass for each optical transmission device in the optical bypass, and sent the set first flow forwarding entry to a corresponding optical transmission device.