A data flow control method, comprising: receiving, by a first gateway, a first message sent by a user equipment through a first access network, wherein the first message carries first Internet Protocol IP flow identification information, and the first IP flow identification information is used to identify an IP flow that is transmitted by the user equipment through the first access network and/or an IP flow that is transmitted by the user equipment through a second access network, wherein the first access network and the second access network are access networks using different access technologies; sending, by the first gateway, a second message to a packet data network gateway, wherein the second message carries second IP flow identification information, and wherein the second IP flow identification information is the same as the first IP flow identification information or the second IP flow identification information is obtained based on the first IP flow identification information; receiving, by the first gateway, a third message sent by the packet data network gateway, wherein the third message carries third IP flow identification information, and wherein the third IP flow identification information is used to identify an IP flow that is allowed by a network to be transmitted by the user equipment through the first access network and/or an IP flow that is allowed by the network to be transmitted by the user equipment through the second access network; and sending, by the first gateway, a fourth message to the user equipment, wherein the fourth message carries fourth IP flow identification information, and wherein the fourth IP flow identification information is the same as the third IP flow identification information or the fourth IP flow identification information is obtained based on the third IP flow identification information. receiving, by a first gateway, a first message sent by a user equipment through a first access network, wherein the first message carries first Internet Protocol IP flow identification information, and the first IP flow identification information is used to identify an IP flow that is transmitted by the user equipment through the first access network and/or an IP flow that is transmitted by the user equipment through a second access network, wherein the first access network and the second access network are access networks using different access technologies; sending, by the first gateway, a second message to a packet data network gateway, wherein the second message carries second IP flow identification information, and wherein the second IP flow identification information is the same as the first IP flow identification information or the second IP flow identification information is obtained based on the first IP flow identification information; receiving, by the first gateway, a third message sent by the packet data network gateway, wherein the third message carries third IP flow identification information, and wherein the third IP flow identification information is used to identify an IP flow that is allowed by a network to be transmitted by the user equipment through the first access network and/or an IP flow that is allowed by the network to be transmitted by the user equipment through the second access network; and sending, by the first gateway, a fourth message to the user equipment, wherein the fourth message carries fourth IP flow identification information, and wherein the fourth IP flow identification information is the same as the third IP flow identification information or the fourth IP flow identification information is obtained based on the third IP flow identification information.