A method for communication system handover, wherein the method is applied to a 5G system and the method comprises: receiving, by an authentication management function node, AMF, a handover request sent by a core network side of an evolved packet system, EPS, wherein the handover request carries first indication information about whether a source node supports direct data forwarding and a target next generation-radio access network, NG-RAN, node identifier; and acquiring, by the AMF, an EPS context of a terminal needing system handover; characterized in that, the method further comprises: sending, by the AMF, a protocol data unit, PDU, session establishment request to a session management function, SMF, wherein the PDU session establishment request carries the first indication information, the EPS context, and the target NG-RAN node identifier; receiving, by the AMF, a response, returned by the SMF, to the PDU session establishment request, wherein the response comprises PDU sessions, a mapping relationship between the EPS context and the PDU sessions, and second indication information about whether the target NG-RAN node and the source node support indirect data forwarding; sending, by the AMF, a handover request carrying the PDU sessions, the mapping relationship, the first indication information and the second indication information to the target NG-RAN node corresponding to the target NG-RAN node identifier, for determining a PDU session needing data forwarding according to the PDU sessions and the mapping relationship and determining the address of data forwarding according to the first indication information and the second indication information by the target NG-RAN node; receiving, by the AMF, the PDU session which is determined to need data forwarding and the determined address of data forwarding sent by the target NG-RAN node; and forwarding, by the AMF, the PDU session needing data forwarding and the determined address of data forwarding to an SMF. receiving, by an authentication management function node, AMF, a handover request sent by a core network side of an evolved packet system, EPS, wherein the handover request carries first indication information about whether a source node supports direct data forwarding and a target next generation-radio access network, NG-RAN, node identifier; and acquiring, by the AMF, an EPS context of a terminal needing system handover; characterized in that, the method further comprises: sending, by the AMF, a protocol data unit, PDU, session establishment request to a session management function, SMF, wherein the PDU session establishment request carries the first indication information, the EPS context, and the target NG-RAN node identifier; receiving, by the AMF, a response, returned by the SMF, to the PDU session establishment request, wherein the response comprises PDU sessions, a mapping relationship between the EPS context and the PDU sessions, and second indication information about whether the target NG-RAN node and the source node support indirect data forwarding; sending, by the AMF, a handover request carrying the PDU sessions, the mapping relationship, the first indication information and the second indication information to the target NG-RAN node corresponding to the target NG-RAN node identifier, for determining a PDU session needing data forwarding according to the PDU sessions and the mapping relationship and determining the address of data forwarding according to the first indication information and the second indication information by the target NG-RAN node; receiving, by the AMF, the PDU session which is determined to need data forwarding and the determined address of data forwarding sent by the target NG-RAN node; and forwarding, by the AMF, the PDU session needing data forwarding and the determined address of data forwarding to an SMF. sending, by the AMF, a protocol data unit, PDU, session establishment request to a session management function, SMF, wherein the PDU session establishment request carries the first indication information, the EPS context, and the target NG-RAN node identifier; receiving, by the AMF, a response, returned by the SMF, to the PDU session establishment request, wherein the response comprises PDU sessions, a mapping relationship between the EPS context and the PDU sessions, and second indication information about whether the target NG-RAN node and the source node support indirect data forwarding; sending, by the AMF, a handover request carrying the PDU sessions, the mapping relationship, the first indication information and the second indication information to the target NG-RAN node corresponding to the target NG-RAN node identifier, for determining a PDU session needing data forwarding according to the PDU sessions and the mapping relationship and determining the address of data forwarding according to the first indication information and the second indication information by the target NG-RAN node; receiving, by the AMF, the PDU session which is determined to need data forwarding and the determined address of data forwarding sent by the target NG-RAN node; and forwarding, by the AMF, the PDU session needing data forwarding and the determined address of data forwarding to an SMF.