In order to achieve the discovery and calculation of interlayer paths, a method for calculating an interlayer path is proposed by the present invention, comprising: a label switch router (LSR) of a layer selecting a path calculation element (PCE) of the layer according to the received discovery information of each PCE and sending thereto a path calculation request for the LSR, wherein the above discovery information comprises: indication information and interlayer information, with the indication information indicating whether the PCE can be used as a default interlayer path calculation element of the layer, and the interlayer information indicating a layer where the PCE is located and an adjacent layer thereof; when a path of the LSR is disconnected, selecting based on the interlayer information a path calculation element (PCE) of the next layer and sending thereto a path calculation request for the disconnected portion of the path until the path is connected; and replying a path calculation result to the PCE of the layer.