A policy control method, comprising: receiving, by a policy decision apparatus, a control policy request sent by a gateway device, wherein the control policy request carries a subscriber identifier; sending, by the policy decision apparatus, a session request message to a charging system, wherein the session request message carries the subscriber identifier; receiving, by the policy decision apparatus, a response message of the session request message, wherein the response message is sent by the charging system, the response message indicating that a session is established; receiving, by the policy decision apparatus, a notification message sent through the established session by the charging system, wherein the notification message is sent when a non-subscribed charging relevant event occurs, the non-subscribed charging relevant event corresponding to the subscriber identifier and needing to be monitored for occurrence, and generating a service data flow control policy according to information of the occurred non-subscribed charging relevant event carried in the notification message; and sending, by the policy decision apparatus, the control policy to the gateway device according to the control policy request; wherein: the non-subscribed charging relevant event is configured in the charging system and is not subscribed to by the policy decision apparatus, and the charging system determines, according to a condition of the session between the policy decision apparatus and the charging system, whether to report the occurred non-subscribed charging relevant event to the policy decision apparatus; and the step of generating comprises: retrieving, by the policy decision apparatus and from preset non-subscribed charging relevant events, the non-subscribed charging relevant event; if the occurred non-subscribed charging relevant event is found determining that the non-subscribed charging relevant event can be identified, performing policy decision based on the non-subscribed charging relevant event, and generating, according to the information of the non-subscribed charging relevant event, the service data flow control policy. receiving, by a policy decision apparatus, a control policy request sent by a gateway device, wherein the control policy request carries a subscriber identifier; sending, by the policy decision apparatus, a session request message to a charging system, wherein the session request message carries the subscriber identifier; receiving, by the policy decision apparatus, a response message of the session request message, wherein the response message is sent by the charging system, the response message indicating that a session is established; receiving, by the policy decision apparatus, a notification message sent through the established session by the charging system, wherein the notification message is sent when a non-subscribed charging relevant event occurs, the non-subscribed charging relevant event corresponding to the subscriber identifier and needing to be monitored for occurrence, and generating a service data flow control policy according to information of the occurred non-subscribed charging relevant event carried in the notification message; and sending, by the policy decision apparatus, the control policy to the gateway device according to the control policy request; the non-subscribed charging relevant event is configured in the charging system and is not subscribed to by the policy decision apparatus, and the charging system determines, according to a condition of the session between the policy decision apparatus and the charging system, whether to report the occurred non-subscribed charging relevant event to the policy decision apparatus; and the step of generating comprises: retrieving, by the policy decision apparatus and from preset non-subscribed charging relevant events, the non-subscribed charging relevant event; if the occurred non-subscribed charging relevant event is found determining that the non-subscribed charging relevant event can be identified, performing policy decision based on the non-subscribed charging relevant event, and generating, according to the information of the non-subscribed charging relevant event, the service data flow control policy.