A method for computing cross-layer separated service paths, comprising: acquiring (101, 202) path information about two physical-layer separated paths from a service starting point to a service end point on a physical network; updating (102, 203) a link cost of each IP link segment on a router network according to the path information about the two physical-layer separated paths, wherein the updating the link cost of each IP link segment on the router network according to the path information about the two physical-layer separated paths comprises: setting, by a network node of the router network, a link cost of IP link segments corresponding to the two physical-layer separated paths to a smaller value, and setting a link cost of other IP link segments to a larger value; and computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment, wherein the computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment comprises: computing (103, 204), by the network node on the router network, the path information about the two router-layer separated paths according to the updated link cost of each IP link segment, wherein both the two router-layer separated paths have a minimum link cost sum. acquiring (101, 202) path information about two physical-layer separated paths from a service starting point to a service end point on a physical network; updating (102, 203) a link cost of each IP link segment on a router network according to the path information about the two physical-layer separated paths, wherein the updating the link cost of each IP link segment on the router network according to the path information about the two physical-layer separated paths comprises: setting, by a network node of the router network, a link cost of IP link segments corresponding to the two physical-layer separated paths to a smaller value, and setting a link cost of other IP link segments to a larger value; and computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment, wherein the computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment comprises: computing (103, 204), by the network node on the router network, the path information about the two router-layer separated paths according to the updated link cost of each IP link segment, wherein both the two router-layer separated paths have a minimum link cost sum. setting, by a network node of the router network, a link cost of IP link segments corresponding to the two physical-layer separated paths to a smaller value, and setting a link cost of other IP link segments to a larger value; and computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment, wherein the computing (103, 204) path information about two corresponding router-layer separated paths on the router network according to the updated link cost of each IP link segment comprises: computing (103, 204), by the network node on the router network, the path information about the two router-layer separated paths according to the updated link cost of each IP link segment, wherein both the two router-layer separated paths have a minimum link cost sum. computing (103, 204), by the network node on the router network, the path information about the two router-layer separated paths according to the updated link cost of each IP link segment, wherein both the two router-layer separated paths have a minimum link cost sum.