A method for long-term storage of cross-domain path information, wherein the method is applied on a stateless path computation element, PCE, and comprises: sending, by a path head node, path request information comprising the path head node and a path tail node to a second PCE corresponding to a second domain where the path tail node is located via a first PCE corresponding to a first domain, to enable the first PCE to compute an intra-domain path of the first domain and generate a first PATH-KEY corresponding to the intra-domain path of the first domain, compute a path from the path head node to the path tail node according to path response information returned by the second PCE, wherein a second PATH-KEY corresponding to an intra-domain path of the second domain is comprised in the path response information, and send the path head node information of the path from the path head node to the path tail node; sending, by the path head node to the first PCE, query information for querying intra-domain path information of the first domain corresponding to the first PATH-KEY, generating, according to a query result returned by the first PCE, a third PATH-KEY having a unique identifier and corresponding to the intra-domain path information of the first domain, and storing the third PATH-KEY for a long term; sending, by the path head node, to a head node in the second domain an inter-domain path establishment signalling comprising the third PATH-KEY and the second PATH-KEY, to enable the head node in the second domain to send, to the second PCE, query information for querying intra-domain path information of the second domain corresponding to the second PATH-KEY, generate, according to a query result returned by the second PCE, a fourth PATH-KEY having a unique identifier and corresponding to the intra-domain path information of the second domain, and store the fourth PATH-KEY for a long term; and modifying, by the path head node, the information of the path from the path head node to the path tail node according to a reverse signalling returned by the path tail node and comprising the third PATH-KEY and the fourth PATH-KEY. sending, by a path head node, path request information comprising the path head node and a path tail node to a second PCE corresponding to a second domain where the path tail node is located via a first PCE corresponding to a first domain, to enable the first PCE to compute an intra-domain path of the first domain and generate a first PATH-KEY corresponding to the intra-domain path of the first domain, compute a path from the path head node to the path tail node according to path response information returned by the second PCE, wherein a second PATH-KEY corresponding to an intra-domain path of the second domain is comprised in the path response information, and send the path head node information of the path from the path head node to the path tail node; sending, by the path head node to the first PCE, query information for querying intra-domain path information of the first domain corresponding to the first PATH-KEY, generating, according to a query result returned by the first PCE, a third PATH-KEY having a unique identifier and corresponding to the intra-domain path information of the first domain, and storing the third PATH-KEY for a long term; sending, by the path head node, to a head node in the second domain an inter-domain path establishment signalling comprising the third PATH-KEY and the second PATH-KEY, to enable the head node in the second domain to send, to the second PCE, query information for querying intra-domain path information of the second domain corresponding to the second PATH-KEY, generate, according to a query result returned by the second PCE, a fourth PATH-KEY having a unique identifier and corresponding to the intra-domain path information of the second domain, and store the fourth PATH-KEY for a long term; and modifying, by the path head node, the information of the path from the path head node to the path tail node according to a reverse signalling returned by the path tail node and comprising the third PATH-KEY and the fourth PATH-KEY.