A communication system for implementing policy control, comprising a user equipment, a session management function entity, a user plane function entity, a policy control function entity, and a core network, wherein the session management function entity is configured to: receive a service policy identifier sent by the user equipment, send the service policy identifier to the policy control function entity, receive a service policy that is sent by the policy control function entity and that is corresponding to the service policy identifier, and send the service policy to the user plane function entity; the policy control function entity is configured to: receive the service policy identifier sent by the session management function entity, and send the service policy corresponding to the service policy identifier to the session management function entity; and the user plane function entity is configured to: receive the service policy sent by the session management function entity, and perform, according to the service policy, policy control on a data packet sent by the user equipment, wherein an application client module of the user equipment is configured to interact with an application server to obtain the service policy identifier, wherein the data packet exchanged between the application client module and the application server is sent or received by using a communications module of the user equipment, and wherein the user plane function entity is set to a proxy or a message forwarding proxy between the user equipment and the application server, in that the user equipment is configured to send a service policy update request to the core network on a user plane, and to push, to the core network, the service policy, wherein the service policy update request includes the service policy identifier, and in that the user plane function entity is further configured to receive the service policy information pushed by the user equipment and to send, to the session management function entity, the service policy identifier pushed by the user equipment. the session management function entity is configured to: receive a service policy identifier sent by the user equipment, send the service policy identifier to the policy control function entity, receive a service policy that is sent by the policy control function entity and that is corresponding to the service policy identifier, and send the service policy to the user plane function entity; the policy control function entity is configured to: receive the service policy identifier sent by the session management function entity, and send the service policy corresponding to the service policy identifier to the session management function entity; and the user plane function entity is configured to: receive the service policy sent by the session management function entity, and perform, according to the service policy, policy control on a data packet sent by the user equipment, wherein an application client module of the user equipment is configured to interact with an application server to obtain the service policy identifier, wherein the data packet exchanged between the application client module and the application server is sent or received by using a communications module of the user equipment, and wherein the user plane function entity is set to a proxy or a message forwarding proxy between the user equipment and the application server, in that the user equipment is configured to send a service policy update request to the core network on a user plane, and to push, to the core network, the service policy, wherein the service policy update request includes the service policy identifier, and in that the user plane function entity is further configured to receive the service policy information pushed by the user equipment and to send, to the session management function entity, the service policy identifier pushed by the user equipment.