A network as a service, NaaS, service cross-domain orchestration method, comprising: receiving, by an orchestration device, a network as a service, NaaS, service request, wherein the NaaS service request is used to request to establish an NaaS service between a first terminal and a second terminal; obtaining, by the orchestration device, information about a first user-to-network interface UNI and information about a second UNI in a multi-domain network according to the NaaS service request, wherein the first UNI is used by the first terminal to access a first network domain, the second UNI is used by the second terminal to access a second network domain, the multi-domain network comprises at least two network domains, and the multi-domain network is between the first terminal and the second terminal; querying, by the orchestration device, domain resource information according to the information about the first UNI and the information about the second UNI, to obtain a cross-domain path between the first UNI and the second UNI; determining, by the orchestration device, network domains that the cross-domain path passes through, and obtaining a first connection requirement and a second connection requirement of each network domain of the network domains that the cross-domain path passes through, wherein the first connection requirement is an intra-domain connection requirement of each network domain, the second connection requirement is an inter-domain connection requirement between each network domain and an adjacent domain, and the adjacent domain is in the multi-domain network; and separately sending, by the orchestration device, the first connection requirement and the second connection requirement of each network domain to a control device in each network domain; wherein the domain resource information comprises a first virtual node abstracted based on a first network domain and a second virtual node abstracted based on a second network domain, wherein the first virtual node has a first UNI coupled with the first terminal, the second virtual node has a second UNI coupled with the second terminal, and each of the first virtual node and the second virtual node has at least one external network-to-network interface, ENNI. receiving, by an orchestration device, a network as a service, NaaS, service request, wherein the NaaS service request is used to request to establish an NaaS service between a first terminal and a second terminal; obtaining, by the orchestration device, information about a first user-to-network interface UNI and information about a second UNI in a multi-domain network according to the NaaS service request, wherein the first UNI is used by the first terminal to access a first network domain, the second UNI is used by the second terminal to access a second network domain, the multi-domain network comprises at least two network domains, and the multi-domain network is between the first terminal and the second terminal; querying, by the orchestration device, domain resource information according to the information about the first UNI and the information about the second UNI, to obtain a cross-domain path between the first UNI and the second UNI; determining, by the orchestration device, network domains that the cross-domain path passes through, and obtaining a first connection requirement and a second connection requirement of each network domain of the network domains that the cross-domain path passes through, wherein the first connection requirement is an intra-domain connection requirement of each network domain, the second connection requirement is an inter-domain connection requirement between each network domain and an adjacent domain, and the adjacent domain is in the multi-domain network; and separately sending, by the orchestration device, the first connection requirement and the second connection requirement of each network domain to a control device in each network domain; wherein the domain resource information comprises a first virtual node abstracted based on a first network domain and a second virtual node abstracted based on a second network domain, wherein the first virtual node has a first UNI coupled with the first terminal, the second virtual node has a second UNI coupled with the second terminal, and each of the first virtual node and the second virtual node has at least one external network-to-network interface, ENNI.