Path computation method and path computation element in optical network

The present invention discloses a path computation method and a path computation element in optical network. The path computation method includes following steps: issuing ring protection information of each link in the optical network by a route protocol message, wherein the ring protection information comprises an identifier of each link and a ring identifier of the ring to which the link belongs; receiving the ring protection information by the route protocol message and, according to the ring protection information, combining the links with the same ring identifier as a ring in order to obtain ring topology information; and performing path computation according to the ring topology information. With the invention, the path which is better than that in prior art can be calculated.