A method for determining identification information about a cross-domain path, applied to a hierarchical path computation element, PCE, network, the method comprising receiving, by a parent PCE, a path computation request from a first sub-PCE, wherein the hierarchical PCE network comprises the parent PCE and a plurality of sub-PCEs disposed in different domains, the path computation request is used for making a request to acquire a path from a source node to a destination node, the source node and the destination node are located in different domains, wherein the path comprises one or more path segments, and the path computation request carries a compression identifier for identifying compression of the one or more path segments and a path setup type, PST; after identification information about the path from the source node to the destination node is acquired, instructing, by the parent PCE according to the compression identifier and the PST, each of sub-PCEs corresponding to the one or more path segments to compress identification information about a respective one of the one or more path segments; and receiving, by the parent PCE, the compressed identification information about the respective one of the one or more path segments returned by the each of sub-PCEs corresponding to the one or more path segments, and combining, according to the identification information about the path, the compressed identification information about the one or more path segments into compressed identification information about the path; characterized in that, the instructing, by the parent PCE according to the compression identifier, the each of sub-PCEs corresponding to the one or more path segments to compress the identification information about the respective one of the one or more path segments comprises: sending, according to the compression identifier, a creation message to the each of sub-PCEs corresponding to the one or more path segments, wherein the creation message is used for requesting the each of sub-PCEs corresponding to the one or more path segments to create a tunnel and assign a binding segment-identification, Binding SID, to the created tunnel, wherein the creation message carries path information about the one or more path segments; wherein after the combining, according to the identification information about the path, the compressed identification information about the one or more path segments into the compressed identification information about the path, the method comprises: returning the compressed identification information about the path to the first sub-PCE. receiving, by a parent PCE, a path computation request from a first sub-PCE, wherein the hierarchical PCE network comprises the parent PCE and a plurality of sub-PCEs disposed in different domains, the path computation request is used for making a request to acquire a path from a source node to a destination node, the source node and the destination node are located in different domains, wherein the path comprises one or more path segments, and the path computation request carries a compression identifier for identifying compression of the one or more path segments and a path setup type, PST; after identification information about the path from the source node to the destination node is acquired, instructing, by the parent PCE according to the compression identifier and the PST, each of sub-PCEs corresponding to the one or more path segments to compress identification information about a respective one of the one or more path segments; and receiving, by the parent PCE, the compressed identification information about the respective one of the one or more path segments returned by the each of sub-PCEs corresponding to the one or more path segments, and combining, according to the identification information about the path, the compressed identification information about the one or more path segments into compressed identification information about the path; characterized in that, the instructing, by the parent PCE according to the compression identifier, the each of sub-PCEs corresponding to the one or more path segments to compress the identification information about the respective one of the one or more path segments comprises: sending, according to the compression identifier, a creation message to the each of sub-PCEs corresponding to the one or more path segments, wherein the creation message is used for requesting the each of sub-PCEs corresponding to the one or more path segments to create a tunnel and assign a binding segment-identification, Binding SID, to the created tunnel, wherein the creation message carries path information about the one or more path segments; wherein after the combining, according to the identification information about the path, the compressed identification information about the one or more path segments into the compressed identification information about the path, the method comprises: returning the compressed identification information about the path to the first sub-PCE.