A method for switching a circuit switch domain service to a packet switch domain, configuring a handover proxy, HO-Proxy, for handover to a Packet Switch, PS, domain of a target network, the method comprising: receiving, by the HO-Proxy, a Circuit Switch, CS, domain service handover request, sent by a service network base station system, for a User Equipment, UE, when the service network base station system determines to switch a CS domain service of a UE to a PS domain of a target network; wherein identifying information indicating that the UE has a PS domain service is carried in the CS domain service handover request for the UE; and requesting, by the HO-Proxy, a target network control entity to switch the CS domain service of the UE to the PS domain of the target network, or switching, by the HO-Proxy, the CS domain service of the UE to the PS domain of the target network; wherein before the service network base station system determines to switch the CS domain service of the UE to the PS domain of the target network, the method further comprising: establishing, by the UE, a PS bearer at a service network or the target network via an IP Multimedia Core Network Subsystem, IMS, or initiating, by the UE, a session, or establishing, by the UE, a PS bearer directly at the service network or the target network; wherein a CS domain service handover request for the UE received by the HO-proxy is: sent by the service network base station system and carries information that can be associated with the HO-Proxy; or sent, by the service network base station system, to a service network Mobile Switching Center, MSC, and sent, by the service network MSC, to the HO-Proxy. receiving, by the HO-Proxy, a Circuit Switch, CS, domain service handover request, sent by a service network base station system, for a User Equipment, UE, when the service network base station system determines to switch a CS domain service of a UE to a PS domain of a target network; wherein identifying information indicating that the UE has a PS domain service is carried in the CS domain service handover request for the UE; and requesting, by the HO-Proxy, a target network control entity to switch the CS domain service of the UE to the PS domain of the target network, or switching, by the HO-Proxy, the CS domain service of the UE to the PS domain of the target network; wherein before the service network base station system determines to switch the CS domain service of the UE to the PS domain of the target network, the method further comprising: establishing, by the UE, a PS bearer at a service network or the target network via an IP Multimedia Core Network Subsystem, IMS, or initiating, by the UE, a session, or establishing, by the UE, a PS bearer directly at the service network or the target network; establishing, by the UE, a PS bearer at a service network or the target network via an IP Multimedia Core Network Subsystem, IMS, or initiating, by the UE, a session, or establishing, by the UE, a PS bearer directly at the service network or the target network; wherein a CS domain service handover request for the UE received by the HO-proxy is: sent by the service network base station system and carries information that can be associated with the HO-Proxy; or sent, by the service network base station system, to a service network Mobile Switching Center, MSC, and sent, by the service network MSC, to the HO-Proxy. sent by the service network base station system and carries information that can be associated with the HO-Proxy; or sent, by the service network base station system, to a service network Mobile Switching Center, MSC, and sent, by the service network MSC, to the HO-Proxy.