A flow control method, comprising: receiving (32, 42, 52, 62), by an access device from a gateway device, processing capability information of an activation request message, wherein the processing capability information of the activation request message corresponds to an access point name, APN, needing to be controlled that is determined by the gateway device, and the processing capability information of the activation request message is a size of an activation request message processing window, and the size of the activation request message processing window indicates a number of activation request messages which corresponds to the APN and the gateway device can load in a current statistical period; receiving, by the access device, the activation request message sent by a terminal; and performing, by the access device, flow control on a processing procedure of the activation request message according to the processing capability information of the activation request message, which comprises: obtaining (33, 43, 53, 63), according to the processing capability information of the activation request message, the size of the activation request message processing window that corresponds to the APN and can be processed by the gateway device in the current statistical period; obtaining (34, 44, 54, 64) the number of activation request messages that corresponds to the APN and have been assigned to the gateway device in the current statistical period; stopping assigning, when the number of the activation request messages that have been assigned in the current statistical period is greater than the size of the activation request message processing window that can be processed in the current statistical period, the activation request message to the gateway device, in the remaining time of the current statistical period; and assigning (37, 57) the activation request message to another gateway device, or, discarding (48, 68) the activation request message. receiving (32, 42, 52, 62), by an access device from a gateway device, processing capability information of an activation request message, wherein the processing capability information of the activation request message corresponds to an access point name, APN, needing to be controlled that is determined by the gateway device, and the processing capability information of the activation request message is a size of an activation request message processing window, and the size of the activation request message processing window indicates a number of activation request messages which corresponds to the APN and the gateway device can load in a current statistical period; receiving, by the access device, the activation request message sent by a terminal; and performing, by the access device, flow control on a processing procedure of the activation request message according to the processing capability information of the activation request message, which comprises: obtaining (33, 43, 53, 63), according to the processing capability information of the activation request message, the size of the activation request message processing window that corresponds to the APN and can be processed by the gateway device in the current statistical period; obtaining (34, 44, 54, 64) the number of activation request messages that corresponds to the APN and have been assigned to the gateway device in the current statistical period; stopping assigning, when the number of the activation request messages that have been assigned in the current statistical period is greater than the size of the activation request message processing window that can be processed in the current statistical period, the activation request message to the gateway device, in the remaining time of the current statistical period; and assigning (37, 57) the activation request message to another gateway device, or, discarding (48, 68) the activation request message. obtaining (33, 43, 53, 63), according to the processing capability information of the activation request message, the size of the activation request message processing window that corresponds to the APN and can be processed by the gateway device in the current statistical period; obtaining (34, 44, 54, 64) the number of activation request messages that corresponds to the APN and have been assigned to the gateway device in the current statistical period; stopping assigning, when the number of the activation request messages that have been assigned in the current statistical period is greater than the size of the activation request message processing window that can be processed in the current statistical period, the activation request message to the gateway device, in the remaining time of the current statistical period; and assigning (37, 57) the activation request message to another gateway device, or, discarding (48, 68) the activation request message.