A service continuity implementation method, comprising: selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, first path information to the target user plane function entity; sending, by the session management function entity, second path information to a source user plane function entity communicatively connected to a second application server currently serving the terminal, wherein the first path information and the second path information are for establishing a forwarding path between the target user plane function entity and the source user plane function entity; sending, by the session management function entity, a second routing rule to the target user plane function entity, wherein the second routing rule specifies that data whose destination address is an address of the second application server is to be sent to the source user plane function entity communicatively connecting to the second application server; and receiving, by the target user plane function entity, the second routing rule from the session management function entity; sending, by the session management function entity, a first message to a control device, wherein the first message comprises location information of the target user plane function entity, and the location information of the target user plane function entity is used to determine that an application server to serve the terminal is a first application server; receiving, by the session management function entity, indication information of the first application server from the control device; sending, by the session management function entity based on the indication information of the first application server, a first routing rule to the target user plane function entity communicatively connecting to the first application server, wherein the first routing rule comprises that data whose destination address is an address of the first application server is sent to the first application server; and receiving, by target user plane function entity, the first routing rule from the session management function entity. selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, first path information to the target user plane function entity; sending, by the session management function entity, second path information to a source user plane function entity communicatively connected to a second application server currently serving the terminal, wherein the first path information and the second path information are for establishing a forwarding path between the target user plane function entity and the source user plane function entity; sending, by the session management function entity, a second routing rule to the target user plane function entity, wherein the second routing rule specifies that data whose destination address is an address of the second application server is to be sent to the source user plane function entity communicatively connecting to the second application server; and receiving, by the target user plane function entity, the second routing rule from the session management function entity; sending, by the session management function entity, a first message to a control device, wherein the first message comprises location information of the target user plane function entity, and the location information of the target user plane function entity is used to determine that an application server to serve the terminal is a first application server; receiving, by the session management function entity, indication information of the first application server from the control device; sending, by the session management function entity based on the indication information of the first application server, a first routing rule to the target user plane function entity communicatively connecting to the first application server, wherein the first routing rule comprises that data whose destination address is an address of the first application server is sent to the first application server; and receiving, by target user plane function entity, the first routing rule from the session management function entity.